Michael Dorn was going to be in Discovery playing a Klingon. Could you picture him in that costume?
If Dorn was appearing as some other new Klingon we've never seen before, yes why not?

But that isn't what I asked. What I
asked is if we're now meant to be retroactively assuming that Lt. Worf was actually 'supposed' to have looked like the new Klingons do through seven seasons of TNG, four seasons of DS9, and multiple movies. Same for all other 'bumpy' Klingons. Is that the inference that the Discovery people are asking from us? Because even the bumpy foreheads eventually got explained (unnecessarily, some might say, but explained nonetheless.)
If the Kelvin/Discovery Klingons
are similarly 'explained', say as genetically enhanced warriors that have been breed to be closer to the proto-Klingon genome from TNG: "Genesis" while living alongside the other Klingons, then there isn't going to be an issue here. If they're not explained, however.... then in all honesty, I find that a bit of a stretch in my credulity. I'm not totally sure I
can justify in my own mind the likes of Worf, Gowron etc having been meant to look like these new guys all along, because the new Klingon makeup is quite a drastic departure from the past, moreso than the bumpy foreheads. It was when they revealed it in
Into Darkness, and it still is in Discovery.
Nerys Myk said:
Yup, same as when the Bumpies showed up in TMP. That's how they always looked. (Then DS9 threw a spanner in the works)
As I say, that never bothered me as much as it did other people.

But the 'bumpies' weren't
that big a departure from the past, simply an extrapolation of it. These new Klingons, both here and in the Kelvin movies before them, are so radically different to anything we've seen before as to almost
require explanation of some kind.
We shouldn't use the word "canon" anyway. The word is being abused, raped, and mistreated in modern fandoms. I prefer "continuity." Much more appropriate imo.
I tend to agree, but the dictionary definition of 'canon' is the officially sanctioned/ordained books and teachings of any given church. By that definition, what several people are saying in this thread is absolutely accurate: no matter what our opinion is, the 'canon' is whatever Paramount
says it is at any given time, and there is no such thing as 'head canon', 'personal canon' or any other such 'canon'.
I do take the point that many people within fandom tend to misuse 'canon' when they really do mean 'continuity'.