Founders can offer to buy the rights back later. I did this exactly - sold exclusive rights to software and team was hired onto acquiring company, years later acquiring company decides to shut down software arm and terminate existing service agreements. I offered to buy the rights plus our team back (for about 1% of the initial sale - they were going to just shutter it all), and immediately engaged the clients in new contracts. That purchase agreement was a doozy, spent more on lawyers than buying the rights back.

There are always things the acquirer can do to not exactly discontinue a product, but effectively do nothing with it.

If you look at the film industry, they are masters of this. Buying scripts and sitting on them etc. A company could buy your widget startup and say they are still selling it, but mail order telephone sales only.