In some ways I see this unbundling as attacking (in part) the wrong problem.
Yes, bundling it in is a big problem - from the users' perspective "I already have X, so why pay extra for Y ?" The big problem is the way all the elements of Office are intertangled in a way that excludes any form of competition on a level playing field. All proprietary protocols tying together the whole edifice, so it's not practical for anyone (regardless of motivation of budget) to provide a realistic alternative for most of the components in the MS software stack.
So for many, even if Teams is unbundled, customers will simply carry on paying for it because the alternatives aren't "neatly integrated" in the way Teams is.
And this is the larger issue regulators need to get their heads around. In a way, the EU browser selection debacle demonstrated what was to come, and how lame (and far too late) any response would be.
We are now to the point where MS's entrenchment in the whole business world is so deep that only state level action is likely to change anything. But even state level customers (e.g. whole governments) are now almost powerless to intervene - if they impose procurement rules that (for example) require fully open protocols then MS can turn round and say "so what else are you going to use ?". To be blunt, I use O365 at work, and "anything but MS" at home - it's like comparing a modern comfortable car with a nice audio system that links to your phone and has controls on the steering wheel with ... an old motorbike with kick-start. The latter will get you from a to b, slowly, and not in what (by modern standards) you might call comfort.
In any case, we say what happens when governments impose open standards clauses - MS went to great lengths to get it's Office Open document format pushed through as an international standard, very obviously stuffing standards bodies around the world with paid shills to vote it through regardless of it's many flaws. For MS, it was preferable to spend all that money to prevent a truly open and good document format from becoming a required standard for government customers as it would have prevented them keeping the (for example) "use anything but Word and your document formats get screwed up" lock in. I could see them using similar tricks if required to use "open" protocols - for example, by using encryption keys that others can't work with (that's one way they block integration of third party DHCP servers with their DNS servers).
But as usual, the real answer is "don't start from here" - action needed to start at least 20 years ago to head this problem off. And some of us were warning back then where we were headed. But the usual "easy life today" trumps "something that might happen 20 years down the line when we won't be in charge anyway".