this is incorrect - inside the sphere of the earth there is a limited supply of gold that is capped. It becomes more and more difficult to get at the remaining amounts just like the halving makes it more difficult to extract the remaining Bitcoin. Probably we will see the same decline in gold mining rates similar to Bitcoin
Discussion
it doesn't matter what the timescale of the "end" of mining is. 140 years like Bitcoin or 5000 years, it's all the same. It becomes rarer with time until at some point you can't get any more and what was made is all there ever will be. And that's fine...
You seriously don't need "another" blockchain. If you don't cap the number of blockchains you just increase arbitrarily the number of tokens in existence. Hence only one of them will become THE token. Otherwise I will hope for Monero+ and then Monero++
Also Lightning doesn't work on Monero, so no instant payments as well as the non-auditability of token supply...
Lightning layer already being worked on scroll to bottom
I think you're underestimating how massive the earth is and how much gold it still has. If anything, our technological capabilities mean our absolute rate of mining gold increased over time unlike bitcoin. And we are STILL mining after thousands of years. Bitcoin's existence also depends on miners mining so it is even more important. Gold can still exist without people mining it.
But even if I concede that point for the sake of argument, there is a 'virtually' limitless supply outside of earth that we will keep mining practically forever.