They were fitting IR supression systems to prop aircraft as long ago as the Vietnam war. It might actually be easier to IR suppress a turboprop than it is a jet engine. Imagine trying to IR supress an A10.
It makes no difference. As E5M said, already in Vietnam War, piston engined prop planes were dead meat vs SA-7 and it's horribly primitive seeker.
Advantage of a prop attack plane is that it is relatively inexpensive to maintain, deploy and employ and flying in co-operation with troops in ground, has high situational awareness. But you can't make it very survivable. Flying low & slow and using unguided weapons brings out the old adage of "When enemy is in range, so are you". You don't even need MANPADS, just heavy machine guns and light AA guns are threatening for this poorly armoured plane. If you start to adding things like advanced sensors, active countermeasure systems and smart weapons, it's no longer cheap but remains a single-role platform. And say what if it turns out your intel was wee bit out of date (see: Yemen) and enemy actually has some capable AD system like Tunguska or Crotale. With F-35, you're fairly safe. With A-10, you at least have a fighting chance. With a prop plane, you're deadest dodo of Deadonia.
I would see some value for that concept for Third world nations fighting bush wars against insurgents whom nobody is interested in arming with up-to-date weapons but for a major power, it seems like a niche of a niche role.