The aircraft that are being floated as light counter-insurgency strike aircraft are going to be turboprops. Modern turboprop engines can produce more power per pound than even the best piston engine, with far less complexity, easier maintenance, and easier access to fuel. (Jet fuel is actually easier to find than the leaded aviation gasoline than even light piston engines require...much less the serious high-octane juice that engines like the Merlin and Griffon were built for.)
The plane you’re thinking of is the Embraer Super Tucano, from Brazil. It’s already in use with several South American countries, and won the USAF competition though it’s tied up in court with the losing company, Hawker Beechcraft. If the court case gets resolved, the USAF Super Tucanos will be built in Jacksonville.
Interestingly, in the 1980s, Piper Aircraft *did* try to produce an upgraded, modern, turboprop version of the venerable Mustang for the USAF as a strike and counterinsurgency. They called it the PA-48 Enforcer. I’ve seen one of the remaining prototypes, it’s at the USAF Museum in Dayton, Ohio.
http://en.wikipedia.org/wiki/Piper_Enforcer
}:-)4
Fascinating... I did not know that.