Given Bitcoin has been 51% attacked by Chinese miners now (refusing to allow an increase in the block size)
There is no consensus between developers and it's the miners fault for not forking the coin to two competing coins? That's a 51% attack?
If there was dev consensus and they refused that would be a different issue altogether.
The (big Chinese) miners have chosen sides here, whether they state it in those terms or not. They have stated they will use Core, which is itself not a consensus among developers, it is a small block solution supported by some of the developers.
The thing works as follows. You have the code (Bitcoin) and for serious changes to be implemented you have to have a very large consensus.
The 1MB exists. Now. It's not a supported "small block solution". The question is what to do next for scaling.
Core has a roadmap with segwit and future block increases.
"Classic" says we hard fork it with 2mb.
So there is
a) what we have right now (this already exists, it's not something "planned" that needs supports to materialize)
b) two different plans for scaling which, if they don't have near unanimous agreement, will result to forking the currency because each one has different supporters.