On another note...
I think the changes in DSC S2 aren't that much more than the changes made for the third and fourth season of DS9 or the third and fourth seasons of VOY.
To go into that in a little more detail:
DS9 S3 --> The Defiant, the Dominion (technically introduced in S2 but that was meant to set up this season), and revealing the Founders of the Dominion are Odo's people. Not to mention de-emphasizing the Bajorans.
DS9 S4 --> Bringing on Worf and breaking the peace treaty with the Klingons. Not to mention making Dukat seem like he'd turn into one of the "good guys", for lack of a better term. Ira Steven Behr has said this was a detour and it took until the middle of Season 5 to get back to where they originally planned to be with the Dominion as the main enemy. And as far as Dukat being a good guy, to quote Dukat himself, "You and me on the same side, Major? It never quite felt right, did it?"
VOY S3 --> Leaving the Kazon (and Vedians) behind, killing off Suder, making Chakotay not be the father of Seska's child after all, getting rid of any remaining tension with the Maquis crew-members once and for all, and (a little bit later) giving Doc a mobile emitter.
VOY S4 --> Bringing on Seven of Nine and having the Borg and Species 8472 in the background as the Main Adversaries. They might have planned to do something with the Krenim but whatever plans they had were truncated and confined to just "Year of Hell".
These all seem to be changes done on the same level as what's being done now.
DSC S2 --> The Klingon War and Mirror Universe arcs are wrapped up and Lorca's out of the picture, so a vacuum opens up for a different Captain. Pike and Spock are brought on, like Worf and the Borg were brought on in DS9 and VOY, and Discovery goes off on a new adventure with a lighter tone, since the war is over and so is Lorca's influence over the ship.