I believe the natural place to be for Bitcoin is around 80% of marketcap share dominance, and this will eventually come as the altcoin bubble pops, because clearly, the utility of the altcoins out there is near 0 except a very reduced number, and this is not sustainable, it is for a while, inasmuch a Madoff scheme is sustainable, but eventually tower of cards will collapse and said cards don't disappear, they will be put into the Bitcoin box making it around 80%.
Right. Perhaps a good 60-80% bitcoin dominance will be a fair estimate. That's why market cap is not really a good measurement specially for alt coins in terms of its real value in the market. Most of the time is it pump beyond believe and then bitcoin dominance falls back. But if you are going to look at it, doesn't really makes sense for a coin to be pumped above 100% and gaining dominance and then the next day it collapses.
This does not mean you should stop looking for good altcoins. Even after all the scams I've been through, I still dedicate some time to altcoin research. It's only a matter of time we see something good coming other than Bitcoin related improvement proposals.
Yes, we shouldn't stop looking for one because there's some coins who has really some purpose and could potentially grow the price. Unlike those pump-and-dump coins whose value goes artificially.