Vlad Zamfir warns of unsolved ethereum sharding issues

I have a bad understanding of sharding, so bare with me and feel free to correct.

Would a fork of some sort be the option to allocate certain functions of a node to that block to only handle that specific subset of action? I.e. a node for transactions, a node for account info, etc. PoS? Raiden?

I know that things such as centralization are options, but that is not what ETH wants to accomplish, or most cryptos in that sense. The centralization would come from the concentrated allocation to supercomputers? Merge mining? I know historically merge mining has been brought up (2 different cryptos using same algo @ same time.)

ETH can't expect other altcoins to pick up the slack, it needs to be a driving force for this issue if it's wanting to remain where it's at, or surpass BTC at some point.