There is a heavily redacted public version of Apple and HTC’s licensing agreement that was discovered yesterday. The ten-year licensing deal includes a “change of control” clause that automatically terminates the agreement if one of the parties get bought out.
Florian Mueller of FOSS Patents discovered the clause. When HTC entered the licensing deal, they brought their subsidiaries S3 Graphics and VIA technologies with them. Both companies were asserting claims against Apple.
If the arrangement hits a rough patch, the companies can reassert their claims. The claims can also be reasserted if one of the companies is purchased. Since Apple has a dominant market position, it is unlikely that they will be bought out. There is a chance that HTC or one of their subsidiaries can be bought out.