Yes they can but only if they come up with revolutionary product and services, i think new ones can do really if they can solve the issues in the previous blockchains at the same.time i think it will be very hard to out play btc and eth because they have moved to the class of assrt now so they will remain the top coins for many years.
But one of the major problem is mass adoption and It will not be solved by making the new versions of the blockchains even though they are faster.