Do so while you can. There will be a last version of MacOS that supports Intel processors at some point in a few years, and I posit that the prospects of getting the ARM version to run on another ARM based platform would be... daunting...
I'm running High Sierra on my Late 2009 iMac 27. And will continue to until I dispose of the system. I do not know if I will upgrade beyond Mojave for my 2014 and 2015 MacBook Pros. I'm fine with that.