The FAA could subsidize the installation of MOGAS tanks for less than what it would cost to fund a AVGAS contest. Expand the EAA or Petersen STC AML. That cuts your lead emission in half which can buy time for some company that sees a lucrative market in a dying GA industry.
Replacing one boutique fuel with another boutique fuel won’t attract anyone long term. Repurposing an existing high volume fuel ( with as little modification as possible) is the answer.