Yes because it is a divergence from the current bitcoin so would mean it is an alternative version of bitcoin so altcoin it is, regardless if more people support it and it becomes the leader it is still an altcoin, in my eyes anyway.
this has somewhat fazed me as well... the original bitcoin didn't have segwit and didn't have larger blocks, so, the bitcoin running now, which has segwit, and the forked one - bitcoin cash, whose blocksize was increased, are both modifications of the original.
so that means the original bitcoin is gone (?) 