I'd leave it in the hands of professionals. I know, I know, that sounds boring. As often as I tinker and putter about with various ideas, I've had my experiences with the game industry and I've quickly learned the difference between professional products and marketing and dedicated fans who want their vision of a game to be reality. What I want for Battletech has no guarantee of sales success, and it's pretty much foolish arrogance for me to assume otherwise. I'd continue in the vein of the current path, supporting multiple eras. Most of my changes would be cosmetic and behind the scenes changes.
If we're assuming that this is "fuck-off money" (my personal measurement for dream wealth, patent pending), I'd get the overall rights away from the current third party (Topps), return the video game rights to all the FASA properties (SR and BT), and work out whatever the mysterious issue is with novel rights/royalties. I'd also looking into an approach with novels that is similar to the approach with sourcebooks (support multiple eras and keep multiple styles available from R to PG). A unilateral standard on product content rings up as lost sales in my mind. I'd find some way of convincing Adam Jury to return for layout, as his shit is just gorgeous. I'd work to transition some of the ownership of InMediaRes away from some parties, if possible. I'd look to move the license away from HMP and get a dedicated team to keep an up to date construction program available. I'd work on an "official" MegaMek with a stronger programming team. I'd change the policy on electronic products to support Creative Commons licenses. I'd then look to tempt back a specific few of the lost freelancers. Outside of that, there's little in the way of setting changes I'd make. I'd look for automation to be added to the MUL, rather than having record sheet PDFs need to be bought, I'd look for membership similar to Battlecorps (or include it as part of BC). Record sheets would be a click away to print direct from the MUL. I'd get an interactive map up and running, and possibly look to sell an offline version of the software for folks to track their own campaigns. I'd get stronger support for Quickstrike and the Chaos Campaign rules.
I think my only rule changes would be minor ones. Potential unjamming for UACs, and a few TacOps rules as standard (floating crits being one of them). After all that, I'd see what the next rules version would look like (as it's probably less than a decade away) and I'd build a plan for splitting rules to into a "Simple" and "Complex" ruleset. You could scale between the two, but it would pull in support of more casual fans while not alienating the other fans. Expanding Quickstrike support would probably cover this option to some extent.
