I do not agree with the TrueCryptonaire sig:
"In the long run XMR has good chances to gain higher marketcap than btc."
BTC can scale off-chain and Monero doesn't, nor through SPV type implementations. At that point, there is no point in using Monero over BTC. It's true, Monero market cap can be much higher than now, even in the billions, but if it was, Bitcoin would probably be in the trillions.
It's possible Monero or Zcash will occupy some type of niche market, but the anon wars of incrementalism would have to end first, and I'm not really seeing how that's going to happen. You would need to subscribe to four ideas for Monero to really do something:
1) Smooth's claim that currency is the killer app of the blockchain (likely plausible)
2) Anonymity is a mandatory feature set of that app (less plausible)
3) Governments would not make the anon currency extremely difficult to use while allowing BTC instead, crippling the anon currency market cap
4) The need to believe on-chain anonymity would be useful in a clearing/settlement network.
If your key feature is not utilized in the likely evolution of the network, you're relegated back to the niche market. That niche market could be worth billions of dollars though, so I guess it's all relative. BTC on the other hand could go to trillions as a settlement layer. There's just not an overwhelming need to make Bitcoin obsolete and switch when both coins operate roughly the same in the end game. Ring signatures will likely block many further on-chain scaling options to boot. So yea, it could be valuable, but likely not a threat to Bitcoin.
Bitcoin cannot scale, until the fixed blocksize issue is fixed. Off-chain solutions in Bitcoin will also require massive increases in the blocksize. Monero has a currently working solution for main chain scaling by using adaptive blocksize limits and a tail emission. As for SPV implementations they serve to allow for the use of Bitcoin on devices with limited capabilities such as certain mobile devices. SPV does not solve the fundamental issue with Bitcoin scaling in any meaningful way.