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.
I think that too, if bitcoins can do it so do altcoins. But I'm not talking about all altcoins, maybe some of them, those who have high potential and those who have a lots of holders. They won't let their coin to drop and do bankruptcy because they have a lots of holders, and they will complain if that drop in just a blink of an eye. Me myself I hold some altcoins in my wallet lile ethereum and waves, and I would like to sell it yet because I trust them that their value will also rise just like the trust I'm giving into bitcoins.
Few altcoins can make it, more will only be just for ashort span of time, it will only depend on the alt used ,it functionality and on what ICO they came from some alts were really useful but they are too many to have all.