Personally, I classify all the new shows as I-Canon: irreconcilable with the future shown in TOS. What’s strange is that they pretend that, officially, they are all equally part of the same canon, as if Discovery and TOS portray the same universe. So I don’t know, I guess a novel about Kirk will tend to have the look-and-feel of TOS with just a few easter eggs from the rest of the franchise, whereas one about Pike will hew to SNW.
They've been pretty consistent in calling them the "Prime" universe...
Prime doesn't always mean first; in math A' is not A, but the first derivative of A, and A'' is the second derivative, A''' third derivative, etc.
Prime in cases of many areas of commerce isn't "First" but "Best Quality" - and from a visual effects standard, indeed these Prime Universe shows are visual feasts.
I don't see Discovery as irreconcilable; only one issue really is a problem: Michael Burnham as Sarek's Ward and of similar age to Spock. We should have seen her in
The Infinite Vulcan... and she's not there. Further, Seasons 3 and 4 are NOT before TOS. And we got to see Pike take the damage that ties right into TOS'
The Menagerie.
I'll admit that
Lower Decks is pretty much irreconcilable not due to timeline, but due to cartoon physics worse than TAS... The separable floating bodypart alien is from TAS and is in LD... but LD is set after Voyager ends and before Picard.
Picard, for its value, is only before Seasons 3+ of Discovery.
And Enterprise is the point where the visual look is incompatible...
One just has to make a few excuses...
Michael may have been away during TAS:TIV. Or Spock is several years older than Michael.
If you ignore the visuals, the timeline issues aren't a problem with Original Universe - only the look.
Remember, in Screen Canon, we only know that there was a war ended with the Treaty of Anaxar... until the Discovery S1 arcs.
We also know that Main Continuity was broken away from, or broken away to, the Enterprise timeline, thanks to the metaplot Temporal Cold War...
it could be very fun to examine the timelines
We have in TOS alone 2 timmeline changes that could make separate timeline planes/branes
TOS prior to TOS:TIY (1.19) which alters 1965
TOS:TIY to TOS: City on the edge of Forever... which alters 1932, perhaps only slightly
TOS:CotEoF to TOS:All Our Yesterdays... we don't know the knock-on effects of K/S/M
TOS:AOY to TAS:TIV (its Sequel!) Alters the timeline in Spock's Childhood
TNG gives us only a couple timeline benders... but Data in the 1800s and Tasha on the Ent C... Everything in TOS/TAS mmay have been altered by the 1800's bit.
DS9 gives us the Roswell Incident and a return to TOS:TTWT...
altering everything after those
Voy gives us a change in the 2020's Bell Riots.
Ent gives us more temporal mischief... and basically, by that point, anything TOS/TAS is already alternate universes...
So Discovery is probably in the post-Enterprise timeline-twisting brane.
And Strange New Worlds is going to be after that...
We don't have one timeline in TOS alone. Before accounting for Movies 4 and the TNG one with the borg,,,
which also alters the timeline further...