Post aren't rewarded d on other platform either where curation/upvotes aren't rewarded. I dont think curation will ever go, but if it did, it would just give more influence to allocate rewards to those who do curate, even if the higher accounts don't want to because they aren't being paid to. I think in general though, there would be less voting overall, even with major accounts opting out. But empowering the "lower classes" this way will likely be beneficial for the platform, and possibly STEEM as well ;)