Bidbots can return 90% of the profit form the bids and curations (similar % to current model ). However, there are some risk associated in calculating the curation and get hit by downvotes. In this scenario, bidbot can share curation profit when curation is matured (i.e. downvoted post will lose curation). The probable positive outcome can be that thrash trended by bidbots can be hit by the downvotes. The bidbot users will lose the the Steem/SBD spent and curation, be careful about using bidbots next time and leave the system. However, it will mostly depends on the downvotes to discourage the shit content creators to back down (to be seen).
However, there are other alternatives for delegation for tokens such as @steemhunt, (or, @minnowsuppot, @leovoter) provides 20% ROI in terms of HUNT, Steem and SBD.