Bitcoin or 2.0 projects are XMR's biggest danger.
It's possible that the long term paradime of PoW is broken. In theory the value that the PoW is protecting is always going to be going up while the percentage of money spent protecting it (miner rewards) is going to be going down.
Also the release curve is ponzi schemed. And if people realize this with bitcoin and it is rejected - then XMR will take the brunt of the rejection along with bitcoin.
The fact that XMR doesn't share bitcoin's codebase and limited slow transactions is a really good thing.
I just don't think dark is the danger to XMR - I think the rejection of bitcoin is a much larger issue.
...
[2] Actual number of atomic units is M = 264 - 1. A minimum subsidy may be implemented in the future with <1% annual inflation to preserve mining incentives.
...
The XMR specification allows for a minimum subsidy with less than 1% annual inflation to be implemented to address both the miner rewards issue and release curve issues.
Edit: Careful meticulous research is very important when considering a coin. I say read every little footnote.