I think a lot depends on how things scale in regards to the lightning network and block size cap. If they fix these issues I don't see many changes regarding alt coins. If a fork is not made and and things like bitcoin classic is not switched to by the miners I think altcoins running on different mining hardware (ltc, eth, dash) will increase, either leveling the field or taking over the number 1 coin. Not likely given the network hash rate comparison but still a potential if changes are not implemented.