Yes, I would believe so. Bitcoin is just technology after all, and technology tend to become obsoleted pretty fast. There are alts queuing up to take it's position, and Bitcoin does not work as it is now. To be fair, there is lightning and sidechains touted as the solution - but I just don't believe those are any "silver bullets", and I believe it's madness to hold the breath waiting for such solutions.

The network effect is (unfortunately) more important than technical superiority, so I never bother looking beyond the top list of cryptocurrencies on coinmarketcap.

Bitcoin, with the hard core vetoing any block size increase, is never going to be the major payment rail of the future.

Ethereum has some problems with centralization of control ("proof-of-vitalik"), and the contract language has some flaws (like 256-bits "bytes"), quite some Bitcoiners have problems with the fact that the ether supply is not set in stone, transaction fees are high and there are scalability issues. I think the biggest issue is that it's difficult to write bullet-proof contract code (as we've witnessed with TheDAO and now with the parity wallet) - it's not so much point with "smart contracts" if it's easy to hide backdoors in the contracts.

I believe sharding and Proof-of-Stake will be good for ethereum, but I'm concerned that it will be only more and more difficult to do such changes as the Ether economy grows.

Bitcoin Cash, at first I was not much happy with this initiative - if being unhappy with Bitcoin, why not back some existing altcoin instead of creating a new? Everything Bitcoin can do, some altcoin can do better. With software and protocols, it's always so that at one point it's best to scrap the old one and create something new from scratch - Bitcoin, being nine years old, is already a dinosaur.

The community brags that the development is decentralized as they have different full node implementations, but after all they are all forks of the Bitcoin Core code. Satoshi may have been a genius, but he was not a top-class developer. I also think it's a disadvantage that the code is written in C - I believe that if one wants to have a rock steady software package handling important business logic, it would be better to use some more modern programming language (Python, Go, Ruby, ...)

On the positive side, I do see that quite some effort is put into building networks now and getting merchant adoption up - and for merchants being tired of the Bitcoin transaction problems, replacing Bitcoin with Bitcoin Cash is technically a simple operation.

Ripple is not a real cryptocurrency, it's a centralized protocol if I've understood it right. I looked a bit into it some years ago, but gave it up. It may have a chance becoming the dominant payment rails of the future, but I hope it won't.

IOTA is very much overhyped, there are security concerns, maturity concerns, concerns about the technical soundness of the project, and even social concerns (like critical technical questions being moderated away from their subreddit), they have some "central coordinator" which is closed source software (to be fair, it's just a "temporary measure", the network is supposed to work without it as it grows - but still, to me that's pretty concerning) and several other concerns.

Litecoin is a Bitcoin ripoff with no real value proposition as I see it.

Further down we have things like Monero, zCash, Dash ... they haven't managed to climb to the top of the coinmarketcap yet, and I doubt they ever will. There are many other altcoins that have promise from a technical point of view - but to get to the top and stay there it's important with both technical excellence and network effect.

One could hope that someone would invent some toolkit allowing decentralized convertibility - that I could send Bitcoin Cash from my Bitcoin Cash wallet, and the receiver would receive Ether into his Ethereum wallet. With decentralized market places and atomic swaps, this is not completely impossible.

I'm concerned that governments, banks and big merchants (say, Amazon) could cooperate to create a new virtual currency. Such a currency could win the adoption race pretty fast, it would be bad for all decentralized crypto currencies.

Personally I'm holding some Ether and Bitcoin Cash.