Not buying this rumor -- especially for the 35. A new flagship L with less technology than its non-L counterpart?
The new 35L certainly will have IS.
Zero chance of an IS ... Shouldn't expect IS for any of their L primes until you reach the tele range. 24L II, 50L, 85L II should tell you the story.
Respectfully, I disagree. Canon is in the process of adding IS + USM + internal focusing + much improved build quality on every non-L prime (3 down, more certainly to come). Carnathan at TDP was surprised the 24/28 IS lenses didn't get red rings they were so well built. And as we know from early testing, the sharpness of these new non-Ls rivals the current Ls stopped down to a comparable aperture.
So these new L lenses must must must offer more than simply a red ring and a weathersealing gasket. A slight IQ bump is not enough.
[the writer gets on his soapbox]
I think some folks need to warm up to the notion that in low light, F/2 or F/2.8 (depending on the non-L prime we're talking about) with IS will dominate
F/1.4 without it. I can't speak to what you all shoot, but when I am in ultra low light + handheld situations, I'm not shooting moving targets. So IS is buys me flexibility in the darkest conditions.
Ray 2021 posted that he leaves his 35L on F/1.4 for low light, cramped conditions. That's exactly why I bought my 28 IS. I would contend the non-L at F/2 with the 3-4 stops of IS would net those same shots at a sharper narrower aperture with a stop or two to spare to stop down further for sharpness OR choose a less noisy ISO. (Again --> flexibility)
Or perhaps another way to put it -- once the Canon users get a taste of the value of IS in low light, why on earth would they give that up?
I think IS becomes the great entitlement of photographers in the next few years -- it becomes an absolute expectation of most users.
Or perhaps way #3 to put it -- if I am not
getting IS with a new 35L, the IQ had better be off the charts better than the very very good non-L with IS.
I know I am in the minority in this opinion, but I'll keep sharing my take.