All known mineral reserves could power the world on exclusively nuclear energy for several thousand years at least.

You got a source for that? Because the one I linked says that we run out of known Uranium deposits by 2100 at current usage rates. Our known Uranium deposits run out mid-century if we use nuclear to follow the IEA Blue Map plan to reduce carbon emissions by 50%, and we run out of even speculated deposits by 2100 under that scenario. Where are you getting “several thousand years” from? Is Thorium part of the mineral reserves to which you’re referring?

It is somewhat unclear how much Uranium is available worldwide (for strategic reasons), but even at current production, supply issues have been known to happen.

Nuclear fission using Uranium is not sustainable. If we expand current nuclear technologies to tackle climate change then we’d likely run out of Uranium by 2100. Nuclear fusion using Thorium might be sustainable, but it’s not yet a proven, scalable technology. And all of this is ignoring the long lead times, high costs, regulatory hurdles and nuclear weapon proliferation concerns that nuclear typically presents. It’d be great if nuclear was the magic bullet for climate change, but it just ain’t.