~snip~
Bitcoin will adopt every new altcoin every time, new altcoin become part of bitcoin if success listing on exchange market and have trading peer with bitcoin or ethereum, when listing on big exchange market excatly new altcoin become part of bitcoin where investor can sell or buy using bitcoin peer. New altcoin have been success with sale investment and listed with big market.
Well, I don't think that bitcoin will adopt new coins because they might find another way to be able to consume lesser energy and also make their blockchain faster rather than adopting new coins instead. Yes, there are too many altcoins but they had different features and different ecosystems had built. But they use bitcoin as a pair of trading when they are listed on the market, seems like what happen to Ethereum.