If this happens, all other crypto currencies will rise up too. The growth of the crypto currency will bloom once more like the last time it hit that height. Well, aside from those facts, this is also a good thing to happen if the BTC will rise up again in such limits because more people will come back and others will come and join us un here again.
Not all, Only the top currency will survive when BTC reach 1M USD, All those shit coins will be gone for good there's no way people will pay $100 per Linda coin so most projects will cease to exist since the market dominance of BTC will surely be at 80-90% level