Before Google, there was dominance of Yahoo. They also never imagined that one day Google will be become bigger than them. So, never underestimate your competitor.
This is a bad comparison, in terms of references and content Bitcointalk is unique and way ahead, whenever a forum about Bitcoin and Nakamoto is mentioned Bitcointalk will always come out as the source, and we also have to consider many of the best projects that you see in the market started here.
I don't rule out that Altcoinstalk will be bigger I've seen its improvement, and it's unique on its way, just like Bitcointalk's own uniqueness, they should co-exist and it benefits the whole community.