One workaround is the use of Fresnel lenses.
This is featured in Canon's DO (Diffractive Optics) line of lenses.
Another 'workaround' is the use of a mirror, but these lenses are only useful for very specific tasks and are usually not designed for the high end market.
Nikon's PF lenses, of which there are only 2 (300mm f4 PF and 500mm f5.6 PF) are worth a look too. I have the 300PF and it's smaller and lighter than a 24-70mm and plenty sharp. The 500PF has been sold out since launch.
I agree with Ken Rockwell's review of the lens except I add that it just doesn't have the color and contrast "pop" of equivalent lenses such as the 100-400 L II zoom. One thing, though, the used price for the DO lens is low.
Another 'workaround' is the use of a mirror, but these lenses are only useful for very specific tasks and are usually not designed for the high end market.