I, like many on here operate an all lycoming fleet, so it's interesting to see their take on it:
Lycoming continues to believe that piston general aviation is best served in total by pursuing an unleaded aviation specification fuel to replace 100LL.
Unleaded Fuels: Avgas by any other name... is Avgas - Lycoming
They seem to be looking for a good alternative to Avgas. This attack is one of many, and ultimately it looks like 100LL will be dead and buried within the next 10-20 years as soon as an unleaded alternative has been found.
As has been mentioned in previous threads, the problem is when you take the lead out you end up with 91UL, which is no good for high performance singles, but fine for your typical spam can burger run or training fleet. It seems from their bulletins that Lycoming are trying to find an alternative, but the reality is that it's a reasonably specialist market, so where is the financial incentive?
From their website it looks like Lycoming would like to see a one fuel soloution, since that would make production costs more reasonable. A two or three fuel soloution would likely see the high performance aircraft paying an awful lot more for their high octane fuel, since the bulk of the market will happily run on the lower octane.