If most NFL execs ( and not just 1 like I read) truly believe he is Patrick 2.0, you will have 20+!teams waiting to draft him with their 1st pick, regardless of their situation. The Chiefs had Alex Smith who was a #1 pick. when they drafted PM.
If you look at overthecap, 4-3 outside linebackers top out at 13.5 M.
The guys you mentioned Mack, Miller, Jones are highly paid because they are edge rushers. Leonard gets some sacks but he doesn't qualify as an edge rusher. Therefore I see his cost being actually slightly less than Nelson. Nelson would likely get 16 to 17. I see Leonard getting around 15.
Something else I was thinking about is there have been analyst that say SF will trade one of those picks because they need more picks. What if the deal is already being talked about if a QB falls then SF gives us back our 13th pick. That would be pretty crazy.
20 M probably not.
At this point the max on guards is 15 M. Given time and the fact that he will likely set the market, Nelson could be at 17M.
4-3 outside linebackers top out at 13.5 M. Leonard could therefore be somewhere around 15.
The good news is that neither of these positions is aggressively increasing in price
I would say that Ballard would likely trade them if he didn't have the money to pay them.