That was exactly my thought in the original SPS discussion.

Another alternative is that SPS proposals, if approved, can be paid directly out the same reward pool that currently pays posts and comments (making the observation that both a "proposal" and a "comment or post" are fundamentally the very same thing: making a transaction to the blockchain that says: "Please vote to pay me").

I think in both cases this is premature if only because the existing implemented, tested and ready-to-deploy code does not work that way, but also because I'm pretty sure people want more confidence in seeing SPS do something useful before more tightly integrating it into Steem. (Those with experience seeing a nearly-identical system work on Bitshares may be more confident, but not all of us have that experience.)