I agree with your overall view of STEEM and SP. There is little doubt in my mind that SP will become a much needed commodity as the DApps onboard users. After all SP determines RC and that is going to be in demand. Even if there is a RC leasing pool, someone will have to be holding the SP.

One point not mentioned is the importance that I see some of the other tokens taking on. Each will have its own reward pool (either SMT or SE). This will enable people to be rewarded for their content through those means with STEEM ending up being a "back end" token.

There will come a time, I believe, where the majority of newer users will not even focus upon STEEM. It will be just an "additional token" paid out on posts. As long as one has enough RCs to do what they want, SP wont be the primary objective.