I am not sure what lowering the supply would do for adoption of the social aspects of the platform

What reducing inflation does is buy time to come up with better models for achieving social growth or see other types of applications (such as games e.g. Splinterlands) thrive to the point where they lift up the entire economy (and IMO they are more likely to do so if not burdened with the extra cost of paying for poorly-working social reward scheme they do not even use).

I am guessing then that the RCs will need to be adjusted to suit also

RCs adjust their own costz via an internal (hidden) market within the blockchain code. The more RCs being used, the higher the RC prices, and vice versa. So in general, no adjustment is needed there, it should all be automatic (with the caveat that RCs are something new and unique to Steem, are currently a "1.0"-type solution, and could benefit from further refinement in any case).