I think there would be a market for someone to make slow speed carbide grinder like the old glendo accufinish. Slow speed or better yet variable speed, 6" diamond discs, reversible, lots of examples on the internet. All kinds of attachments, fixtures are possible for sharpening specific tools.
I enjoy repairing old equipment, I know a logger that uses old equipment, he is always bringing me something that is worn out, replacement could cost thousands even if it is even available. I look at the part, try to figure out what it looked like new and why and design and build something at least as strong as what it was new. Often involves the welder, lathe and mill. It seems like there are 2 types of people in logging and other trades. One buys new equipment uses it, and has high overhead (loans) and high production, trades up when it starts having problems.. The other buys used equipment, pays for repairs (in cash) instead of loans, accepts lower productivity.