I think it has a chance at becoming a settlement layer or store of value, so will be a digital store of value rather than digital cash. I think something like NEM or Ripple is best placed for the digital cash front. Bitcoin has the advantage that it was the first.
I agree with your statements(hence why I gave you a merit), except this part. I really don't know about NEM, but XRP is simply too centralized to be a method-of-payment coin. Like, it has a CEO, might as well use a debit card instead, or better, physical cash for better anonymity.
I'm personally still betting on the lightning network for the future. If it "fails", then there will likely be more solutions. It's pretty much just a matter of when. The altcoins we have right now that are aiming to be for-payments are mostly just speed. I personally think security and decentralization is still far more important than speed.
I think that speed is important for smaller transactions, whereas larger one's security is important. To be fair, your point about XRP is a very valid one (single point of failure as well, notice i mentioned something like NEM or Ripple, but not necessarily those two), ripples problem is a problem than NEM does not have as much (it uses a consensus mechanism called proof of importance which I find better in my own judgment than PoW or PoS, though PoW is better than many of the other options out there. If you are buying coffee with your Bitcoin, waiting for it to confirm would be tedious, same as if you were at a checkout. For larger purchases, like an expensive laptop, house, your monthly rent, etc security/decentralization wins hands down. If you wanted one cryptocurrency to do all those things, a delicate balance needs to be struck. The lightning network, if made easier for the average joe would solve the problem of coffee payments being slow, and the blockchain would be the settlement layer I described.
Crypto is still young, there is so much potential, but where and how it goes is as yet, unknown. It is interesting. I won't ever pour my life savings into it, but I have invested a small amount, as I think it has potential in the long-term to be a game changer.