Real-world-based, racing related, that would not compete with rF2 and still leverage ISI's physics forte:
- Motorcycles
- Offroad racing
- Rally
- Rallycross
- Dirt track
- Drag racing
- Heavy vehicles (tanks? earthmovers?)
- Hydroplanes
- Offshore racing
Per the original announcement of Studio 397, ISI did not sell rF2, but are a partner in the enterprise known as Studio 397. The earlier words from ISI, before the creation of Studio 397, was that "not rF2" has technology which could find its way into rF2. My hunch is rF2's DX11 lighting & VR development are some of that technology, which would indicate "not rF2" will be a DX11 product.
The world of drag racing is under-explored in games and sims, so that seems like a possibility, though likely too narrow for a single product unless it also tackled the history of drag racing. Motorcycles were explored in the games marketplace, but the lack of affordable & reasonable-size FFB controllers is a marketing hurdle which would need to be tackled. I recall hearing that ISI were involved with military contracts initially, so maybe they have experience with tank simulation?
Offroad/Dirt track/Rally/Rallycross, however, is a larger niche which has a proven market-share, so an all-encompassing title with superior physics could do very well... yes, I can easily see ISI taking on this project (just hope someone else takes care of the UI).