These are real risks to these companies.
Your in-house teams can build replacements, it's just a matter of headcount. With Claude, you can build it and staff it and have time left over. Then your investment pays dividends instead of being a subscription straight jacket you have to keep renting.
I think there's an even faster middle ground: open source AI-assisted replacements for SaaS are probably coming. Some of these companies might offer managed versions, which will speed up adoption.