That also doesn't change anything about bitcoin's fungibility as a currency. 1 bitcoin is always 1 bitcoin whether it is virgin coin, mixed coin or a "regular" coin when you want to use it as a currency not in some centralized service like for trading.
Bitcoin is
not fungible. There is already a pool that only mines "clean" transactions. Of course, it doesn't matter much yet for its small hash rate and the only block I know they've mined was not perfectly "clean" too (by their rules), but it can be a dangerous trend for 5 or 25 years from now.
Monero
is fungible, hence it's a problem for governments and it faces a lot more barriers Bitcoin had. It's still difficult to foresee what will its future look like, if any.
XMR needs to get it's UX/UI better and I think it would have serious potential. It's just too much of a pain to transact with for the average Joe who has little-to-no tech skills. It's a great piece of tech though.
One thing that's for sure is that the tentacles of the trad banking system are going to try to wrap themselves around BTC more and more in the coming years. I just hope the devs and people working on BTC are aware of that and thinking about what adjustments or upgrades the protocol might need in order to maintain it's initial vision of sound money outside of any centralized control. Saylor even hosted a meeting with Elon and N. America BTC miners to try to move towards a "greener" mining opperation.