Realistically, I don't know what to expect next from them, but I know what I can dream about.
They are coming out with a new 30mm f/1.4 for crop cameras, and I'd bet huge that it's going to be very nice. Not sure I want to buy anymore crop lenses, though. The 35mm looks more than good enough to work toward buying.
My dream lens (I know that's another thread, and I'll post this there too when I feel like looking for it)...would be...a very fast medium zoom. It's probably impossible to design and/or build, but here it is: A 60-115mm f/0.8. Even throw in 5 stop IS, or "OS". Expensive? Sigma's version would probably cost $12,000, and Canon's would cost $1 trillion. (Or maybe by then, with the coming inflation, it would cost a $Googleplex) Canon's would be part white, part metallic black, some exotic nano paint finish...with a red stripe around the front made from the red paint chipped off a museum-stored Ferrari 250 GTO. And every snob whose day job is plastic surgery or pro ball, would own one...they'd happily fire two of their collection of mistresses to help fund it.
If Sigma built it, everybody who couldn't quite spring for $12,000, would slam it as overpriced crap that is useless, with terrible bokeh!! "Another Sigma product not worth owning." They would say the tripod mount is made from cheap plastic, old ground up tinker toys and play-dohhh.
They could call it Da Vinci, The Literati, Michelangelo, Sistine Chapel, "the scream", the "magic bowling ball"..."The Return of the Gangsta Dali"...."Lindsay Lohan's Little Helper"...or whatever! Canon would just call theirs the "EIL Mark Nought", for "extreme infinite luxury". There would be waiting lists...and the product would be announced 10 years in advance of it hitting the shelves. Their top photographers, would of course get to use working samples the day the first prototype is produced, and would happily wave that in our faces. Shots would be taken using it, of Richard Branson entwined weightless with a nude supermodel who could care less, in his spaceship. Annie Leibovitz's shoot would include Mick Jagger dressed in a pink pirate outfit on a beach...