If we combine a non-linear with increased curation, the result will be auto-voting to those we expect to earn the most and even less curation.

Even with 'linear' rewards, many are front-running bots to maximum their curation rewards. If increasing curation rewards to 50% can convince the largest stakeholders to undelegate from bots, front-running is going to be more difficult. Whale accounts can also counter front-running by voting exactly on 15 minutes for their regular favourites.

I am quite disappointed regarding the focus of many of the large stakeholders on accumulating Steem rather than increasing the price Steem by promoting content new users would actually want to enjoy. If we assume a constant market cap, vote selling is only going to produce 10% annual ROI at best. Attracting new investment could do that in a day.