87.7 is a frequency that has been open on FM since TV’s digital transition in 2009, which cleared most TV signals off of channels 2-6. (Digital TV stations now identify as “virtual” channels. KRON/4, for example, actually radiates on Channel 38). The audio signal for the old Channel 6 is at approximately 87.7, and it’s cool for a low power TV station to broadcast there and to bypass video altogether, or close enough.
In other words, you might be able to get an FM station going on 87.7 through a license to operate a low power TV station on Channel 6. That’s what WNYZ-LP does in New York and KSFV-LP (which operates as Guadalupe 87.7) does in Los Angeles. And it’s what KXDP-LP (ESPN sports) does in Denver.
KQED might object, even though 87.7 is four channels away from KQED’s 88.5. So might 17-watt KECG in El Cerrito or 7-watt KSRH in San Rafael, both of which broadcast on 88.1. Or 10-watt KSFH in Mountain View on 87.9. NPR might object too, given its ongoing opposition to the practice of operating an “ersatz” TV station just to put a radio signal on 87.7fm. But they also might not care.
Operating a pirate on that channel is also an option. It’s not a legal one, but it seems to fly as long as nobody objects. “Hot 97” in Boston has been going since 2009 at 87.7, showing up shortly after WLNE-TV in Providence/New Bedford abandoned Channel 6 (it’s now on Channel 49). Hot 97’s power isn’t published, but I’ve seen reports saying it’s 5,000 watts. I wouldn’t be surprised, since it’s bigger than many of the noncommercial signals in town, and nearly competitive with the commercial ones. (I first wrote about it here.)
While I wish the KUSF community well in its fight against USF and USC (and maybe also Entercom and the FCC), I think the odds of getting 90.3 back are between slim and none. The best option is to explore other ones.