Absolutely. I'd say it will be a viable machine beyond 2 to 3 years for the majority of people. Given the performance and specs of these modern machines, I can see them lasting easily 5 to 7 years. Specific use cases, could alter that of course but just speaking in generalities.
I think that's a decent price, I'd probably like to see it a little lower but Iyou don't mention the storage, so if that is also rather high and then its in the acceptable ball park - at least I would consider it.
Better is subjective. An M1 with 64GB of ram isn't a couple of grand more, its nearly 4,000 dollars. If you drop your configuration down to 32GB of ram, then the price is 3k. I find both of those prices outside of the range of my budget so I feel they're too high but that's me.
Finally, what are you looking to use the Mac for? I find that i9 has some advantages over the M1, and that's the ability to run x86 code natively and more specifically you can run windows via bootcamp. This gives you the best of both worlds - if that's something that you may want.
The M1's advantages as I see them are. Better battery, and a quieter experience, i.e., less fan noise. So depending on your needs and expectations the M1 is a great machine but for a significantly higher cost, whereas the i9 offers great performance and will be a fine machine for the foreseeable future.