The two older TS lenses seem most likely "specialist" options, refine the design to match the two L versions, slap a big price increase on, make the lenses for less, thus double the profit. I don't really see the macro lens nor the 100-400mm as specialist in the context of EF lenses, but they certainly aren't mainstream.... TS & Fisheye are specialist to my mind. The concept of a 120mm TS Macro is outside of current thinking, but possible I guess
Mainstream update ? It's got to be a zoom, it's highly likely to be a kit lens, the 24-70mm is 9 years old, the 24-105mm is 6 years old... My money would be on the 24-105 personally, as it's probably selling in bigger numbers as it's a cheaper lens - Canon has a profit gain option, or they could take the IS to 4 stops, add hybrid IS, perhaps even shave some weight off the current.