If the company has a legal monopoly that prevents competition, sure. Otherwise, unless they're dumb and want to risk the other two leaving, they'll task all 4 of them to use the AI to accomplish things that were infeasible or uneconomical before, to try win market share or increase margins.
This might be the case at startups.
For mid to larger size companies very often it is though: "we have X amount of work/projects/maintenance/support to do. How many people do we need and how much do we need to budget for that? Oh we need about 4? Will 400,000$ do? Okay let's go". In this case yes. If a $200/month AI subscription can bring those 4 people down to 3 or even 2 of course the company will lay off.
Not op, but…
Just because a company is profitable doesn’t mean that they make good decisions around hiring.