[brezelgoring]

You can still decompile the binaries for Office products today, they are desktop products after all. Same for the Adobe CS suite, AFAIK.

What you can't do is decompile the server-side stuff. In case that stopped working somehow, you could find a way to remove the dependency on online stuffs from your desktop product, it's been done before, often in cracks.

If they fully move to web based SaaS and abandon desktop implementations completely, then yes, you'd be right, you'd no longer be able to modify it in any way.