I am confident that the Bitcoin will not be any major changes.
This is an old and heavy coin with tightly in it ingrown specific Asic chips and different contradictory community.
Ongoing debates about the block size and the absence of agreement on this issue well demonstrated it.
Some alternative coins, on the other hand are more active and rapidly improving for taking all the best, and using the time-tested technical innovations.
So Bitcoin price growth will gradually slow down (in spite of the decrease awards in the coming time).
A qualitative altcoin with active communities will only get more expensive.
Damn what you're saying is really frightening :/
(at least for someone not having investment in altcoins and all in btc)
There is one point you don't consider though. Size issu isn't a direct threat.
It's more about long term effect, or at least mid term. So the actors don't HAVE TO agree on something quick.
But considering the number of actors, and the amount of investments in the btc field, I doubt they would let the currency sink...
But just in case, you have an alt to suggest I should take a look to?

At the moment I have two main asset is the Diamond and Worldcoin.
DMD is a good investment coins and WDC in the future will replace place LTC as fast and convenient coins for instant payment services and shops.