I feel at some not so distant point in future I'll be forced to evaluate alternatives to Bitcoin, because Bitcoin's features I've enthusiastically embraced in the beginning will have been changed beyond recognition.
Bitcoin will always be massively decentralized with thousands of full nodes. Just because I can't currently run a full node on my smart phone doesn't mean that it isn't decentralized. If someone can't run a full node through a 56.6k modem connection routed through TOR that doesn't mean that bitcoin isnt still massively decentralized.
The problem of finding max block size based on some type of network consensus (consisting of full nodes) will ultimately be solved, just as the solution of adjusting difficulty solved the problem of hashing power increases.