It's probably better not to use the term at all in these cases. And just wait until the dust settles before labeling anything an altcoin. That was probably a mistake. Actually now that I think back on it I think I remember LukeJr being one of the first to start pushing that label, and I was annoyed that he and others were trying to expand the definition of an altcoin.
I tend not to even use the expression "altcoin" these days, it's not really meaningful now that there are at least some cryptocurrencies that do a different job to Bitcoin, have a following and are somewhat independent of Bitcoin's price dynamics. Whether those coins are doing their job well is another question, but it shouldn't be decided with perjorative language like "altcoin".
To say "something's called Bitcoin when x & y happen" is total nonsense. People can, and will, label any object or phenomenon with any name they like, and there's nothing anyone can do to stop that (especially not with childish rules, lol).
Bitcoin is a label, and labels can be either good or bad in connotation. I don't care if the current Bitcoin continues to be called Bitcoin, only that the tech improves to increase everyone's liberty. At some point, it might possibly be useful if Bitcoin became completely rebranded, as the majority of people have a negative impression of Bitcoin as a brand right now.