..., are both modifications of the original. 
so that means the original bitcoin is gone (?) 
so that means the original bitcoin is gone (?) Your not the first one to ponder over questions like that: https://en.wikipedia.org/wiki/Ship_of_Theseus
After lurking for a while I have found that you get more political and ideological based answers than scientific ones (maybe not in in the more technical oriented subforums). So I suppose you could just make up your own mind on what is an "altcoin", if any, of those two. It is really not more than a label anyway.
I'm with BrewMaster's interpretation re: which of the two will be labeled alt. Majority versus the minority thing. Still, with the old "tweaked" resulting in these two chains to watch, which chain will be more successful? Perhaps it's still too early to tell since regular transactions have not yet fully resumed. And the timetable did say more action coming up on November. Maybe we'll be seeing more action in the coming days
Edit:
meant to say -- more action coming up til November...