The "power inversion" (or power shift, or decentralisation, or democratisation of markets or hobbyist social replacement of markets, or birth of the information age) is a trend in progress in our society, fueling and fueled by the internet. With the tools and collaboration potential our middle classes have combined with the spare time some classes of society have attained, hobbyist efforts can be used to create things of traditional value, and because we tend to think of these things as hobbyist, our decision not to charge for them combined with the potential for higher quality (with some kinds of information age "products") leads to the destruction of several traditional markets, a burst of social creativity/activity/fluidity, and following from those two, a feeling of empowerment and liberation from tradition. With the opening of media, anyone has the potential to reach an audience and traditional media sources are heavily threatened.
The risks of this are akin to other massive power shifts a society may undertake, e.g. experimenting with a different form of government. One attribute of the shift is that it catalyses many other potential shifts - by making distance less of an issue in forming subcultures, the natural number of subcultures present at a given time should increase a great deal, and the lack of distance combined with less of a feeling of reality over narrow communication devices (e.g. cellphones but especially IRC, IM, and similar) will likly lead to more rapid turnover for subcultures as well. The degree to which this threatens larger coherence of the society and the effects of more numerous fluid subcultures are uncertain. Similarly, difficulties with relationships between people may suffer - a more active memetic ecosphere leads to more differentiation of interests as well as less commonality on basic prerequisites for friendships and deeper connections. A society where everyone is poly and intersted in math (try not to get too excited, some of you!) or a society where everyone is monogamous and most people share an interest in current events may flow more smoothly than mixed social groups, especially as the number of potential "dealbreakers" or critical differences in style goes up. A decreased feeling of societal interconnectedness/belongingness could lead to problems. Another factor, which may end up being only transitional (although I am not convinced it must be) is the risk of cannibalising good things in the transition - as traditional markets fall to hobbyist replacements, some media and other societal may be permanently or temporarily lost, due to an insufficiently financial/social base for non globalisable aspects (e.g. newspapers, which are radically changing as primary gathering of sources does not change but presentation does) - such a system may be stable up until the point when traditional acquisition of facts is threatened, after which re-reporting begins to suffer as profit for media sources it relies on are cannibalised. Finally, radical individualism, to the extent that it is tied to these developments (and may be tied to either immaturity or particular aspects of our culture) poses challenges in social arrangements involving creation of new systems that use authority. This was not always the case - many parts of the internet built before radical individualism was a major force in this cultural change made use of new systems of authority (usenet moderation, for example) that emphasised duty towards a common goal and limited obedience/acceptance of judgement of small numbers of people who guard those community interests. The tension between tendencies towards guardians and risks of ego/corruption of those same have long been a feature of civilisation - developments in society that are excessively egalitarian (that is, in actual organisation rather than regarding privilege -- antistructuralists/those with issues with the concept of authority) will suffer the many costs relating to that - end of individual strivings to improve, poor decisions made in the heat of the moment, etc. Political maturity requires moderation on this issue.
The risks to this are simpler - the continued success of this transformation/social state depends on our ability to provide sufficient cultural continuity that these things are valued enough (or, unrelated to culture, natural enough) that they will be carried on through future generations, that the transformation is sustainable (see above), and the basis of this arrangement is not threatened. The first matter is not necessarily difficult - being social and being creative are potentials in our species, visible from childhood without particular training (that is, they do not require refinement to be sufficiently present to be a drive) - provided technology continues to make possible and enhance creativity, and provided collaboration/communication as a value (also more-or-less inherent) is not stomped out, sufficient cultural continuity should not be difficult. The primary threats to the idea come from threats to its basis. We might expect these to come from two directions, conspiracy and shifting macroeconomics. On the first front, businesses threatened by these shifts may be able to acquire and control critical resources to hamper or prevent cultural shifts - expensive webhosting, excessive lawsuits against sites like youtube/internet archive/4chan/google/amazon/etc, lures to pull people back to corporate content, and controls over ISPs, these are threats that our current property system combined with economic realities could be used as tools to slow change. Macroeconomic shifts affect the other side of freedom - if our middle class should shrink/disappear, perhaps due to decreased neocolonialist economic status of Western Europe and North America, or perhaps due to globalisation being used to subvert age-old improvements in labour standards in those areas, education and free time, two important ingredients for sustained change, may disappear.