I bought a 16" 64GB, 2TB SSD, 5600M in September as well.
I love it! I freelance and it's my only machine. Having upgraded from a 16gb 13" machine (integrated graphics), this 16" blows it away.
I'm so happy with this 16"mbp that I have no feeling of regret or "what if apple releases something better in 12 months?" questions. AT THE SAME TIME, I'm also really looking forward to seeing Apple's GPU solution to their chips. I'm happy with my current machine and also looking forward to Apple continuing to innovate.
Having spent $4200 on this machine (edu discount, zero taxes in NH), I feel I got a decent deal. And I hope to use it for at least 3 years, hopefully 4 (depends on how fast things advance by then). Well worth it to me if that's the case. I'm not worried what I'll be able to sell it for, as this machine helps me make money and I'm using it now. There isn't even a 16" ARM option. There isn't even an ARM computer with better graphics. There isn't even an ARM computer with as much memory.
Be careful not to get too caught up in Apple's marketing (Apple is really good at it). Although if the battery life is important for your workflow that's a solid reason to get it.
If you're trying to stay ahead on depreciation... honestly those 13" M1 machines are going to look old and lose just as much exponential value when the newly designed form factors come out. The average consumer doesn't know what intel i9s or M1s are. But the shiny new design is what will make the "old" laptops depreciate.
Unless you are in the market for a new laptop now, wait until the new designs come out. But I wouldnt sell what you currently have just because of M1 envy or trying to stay ahead of intel values dropping.
That's my take on it.