I think in short term every thing is possible as we experienced high increase in prices of most of major altcoins such as Ethereum. But in long term everything depends on what will happen to Bitcoin.
In my opinion in future we will have only one acceptable cryptocurrency. If Bitcoin can solve its problems like high transaction fees that you mentioned, It will be that cryptocurrency. If not we should wait for another cryptocurrecncy that will replace Bitcoin.
We should also consider another important issue which is governments decisions. In future after accepting bitcoins by entire world, Governments would like to have more control on the system. We should wait for their decision whether they want bitcoin to be that major cryptocurrency or not.
Exactly only few altcoin has the potential to have a bright future. But honestly speaking like what youve said bitcoin was showed the big improvement of it as we see right now. If the problem to the transaction fee would be solved as soon as possible then it might remain in the future. But if not I think we should wait for some altcoin that can replace bitcoin. The future of altcoin depends on what is happening right now so if it good and stable right now then it will have a bright future like bitcoin.