FWIW: if you have a French- or Swiss-threaded frame, it appears you're not limited to square taper cranksets any more. Hollowtech II, GXP, and 30mm spindle cranksets are apparently now an option.

A firm in Israel is offering French- and Swiss-threaded 24mm Hollowtech II bottom brackets - with a 24-to-22mm adapter included to allow GXP crankset use. They also appear to have a French- or Swiss-threaded 30mm axle BB as well.

https://www.roi-cycles.com/bottom-brackets

No, they're not exactly cheap. But all things considered, they not exactly outrageous either.