There must be some new idea to make any or altcoins more mainstream. For sure any more clones of already existing coins doesn't help, but most of altcoins will be doing fine as long as people would be using them.
The ultimate coin will be very different to anything that exists today.
Whatever it is won't be based on the current Bitcoin client or existing protocol.
I believe there will be a separation of transaction confirmation / processing and mining at some point in the future.