In order for it to be a "bubble", the collapse needs to be severe enough that it has a downward momentum. Enough so that even companies with good business models are affected & become undervalued.

I don't see that happening. There are lots of companies with strong business models (Google/Apple/Amazon/Etc) which will be fine if all the revenueless startups suddenly go away. They'll probably be happy they get to hire up all the newly unemployed talent.

Remember.. just because a downward correction is coming, doesn't mean it's a bubble.