MS should be more vulnerable, due to everything but Excel being toilet blockages.

TLDR; MS already got big by being like IBM, lots of dumb corpo procurement cash is already keeping them afloat for about as long as qwerty keyboards - because some people got really good at/dependent on excel.

Their dominance of corpo-procurement (and using 'security' to block out alternative tooling) means that vast amounts of the corpo world is based on highly specialised and over-stretched excel.

Even in databases, where my organisation (large public sector) should be having a genuine competition to administer postGRESQL for us or something, has been loss-led into into a big new ms fabric contract by them appearing to undercut the incumbent (Oracle - ok not hard to undercut), but not actuall . . . [rant deleted]

However, crap MS is at software, they're extremely good at getting dumb corpos to sign on the dotted line.
('always has been' meme). And many humans being forced to use the only tool available, have built vast intricate systems on the foundation of that excel, many of them masterworks of skill in the face of those constraints. Hopefully they don't last as long as one of the old Egyptian dynasties.