In the hypothetical where rideshares on SpaceX suddenly cease to exist or to be available to European companies, ArianeSpace would be delighted to have the opportunity to replace them on similar schedules, and would be able to spin up extra rideshare missions to meet that sudden demand for their services reasonably easily (certainly far more easily than SpaceX or anyone else in the industry could nearshore their entire supply chain fwiw; it's pretty obvious your use/rely distinction cuts the other way). SpaceX owns the LEO rideshare market because they can turn a profit at prices others can't match, not because 3 Transporter missions per year is a difficult launch cadence.