I don't know, maybe you're right, or maybe not.
IBM PC's knocked all the others out of the park. Yet IBM is out of the PC business today. The decline was a slow transition that lasted a decade or more. So it wasn't a shocking disruption. Still, today's computers on the market are the inheritors of the original PC.
I suspect some other coin that will fork off from Bitcoin will be the dominant inheritor because it will add all those bells and whistles that the great alt coins have. Contracts from Ethereum. Privacy from Dash. Etc.
My thoughts for today's age ...
Diversify.
I don't think so ... just like you can't add all the bells and whistles of a modern Tesla to the old Ford ... sometimes it's good to redesign something from the very start.
Software has the luxury of being edited, automotive engineering also can be edited pre production anyway, the finished products cannot be changed(Compiled Software, a Vehicle).
I agree with a couple others here that bitcoin will dominate for a couple years due to it's network effect and then as other altcoins allow visa level transactions and easier banking capabilities the flow out of bitcoin will trigger development to capitalize on the required hard fork like BCC allowing protocols to be upgraded.
I also think that bitcoin's slow transaction time has a benefit where it prevents the madness that is Wall Street NASDAQ Ultra High Speed Computer Computer Trading. While good for price arbitrage not so good for anyone honestly trading values.
At some point it's almost always cheaper to rewrite software from scratch (or replace old software with new software) rather than trying to fix old software. Software tend to turn into junk due to bad design choices from the start, due to code slowly into "spaghetti" due to "technical debt" as more and more features are added improperly and without sufficient maintenance, or because the programming language of choice is getting arcane or encourages the programmers to create "spaghetti code". I don't see the Bitcoin Core code being any exception.
Bitcoin is also a protocol. There has almost become a cult movement that changes to the protocol makes older clients incompatible ("hard forks") should never occur. The block size limit has been discussed for many years, perhaps we'll get an upgrade in November, perhaps not. Now, of all protocol improvements requiring a "hard fork", increasing the block size ought to be the least controversial and easiest thing to do - considering how difficult it has been to move this one, I don't have much hopes for doing other changes to the protocol.
Bitcoin has numerous design weaknesses and problems (personally I think the mining centralization is possibly the biggest problem) - SegWit was an attempt on solving some 3-4 design flaws. Well, I'd say it's more of a work-around than a fix. The main selling point of SegWit was that it's backwards compatible ("soft fork"), as such it's complicating the protocol as well as the software, generating "technical debt".
Everything considered, from a technical point of view, Bitcoin will never be able to compete with the best of the alt-coins.
Such trading will always occur "off-chain", typically on the bigger exchanges.