I still haven't heard a good excuse for core dev concentration in one for profit company other than "trust us".
These are two perfectly good reasons and really the only reasons you need:
1) open source code
2) consensus execution of that code by miners voting with their processing power
Again, why wouldn't we expect a SC fork of bitcoin with perfect anonymity to take over?
This is not so black and white. I suppose there could be a real threat of a side chain taking over if there is little to no perceived risk by the market to move from chain to chain, but if the market perceives little to no risk then maybe there is little to no risk. Savers will likely park their money in the safest chain, i.e. the chain with the highest hashrate and bitcoin could cease to be the dominant chain at some point. I don't see why it couldn't happen.