It can happen if and only if their version of the F-15 can be equipped with air-to-ground weapons. I know the USAF wanted an absolutely pure air superiority fighter, and a superpower needs and can afford that sort of aircraft. West Germany needed a multi-role aircraft, as powers of that size do. At least, it needed a fighter that could drop bombs if the need or opportunity should arise. The F-4 could already do air-to-ground. So I think it's largely a question of how easily the F-15A/B could be equipped for air-to-ground. It need not be more than Mark-series iron bombs and some cluster bombs (as I saw, the F-4F had AGM-65 Maverick support added later). That could be trivial, or it could require a complete rebuild of the avionics and cockpit to provide a bombsight of some kind and the ability to use air-to-ground hardpoints and weapons.
I don't know when the F-4Fs were ordered, but politics comes into play here, too. The SPD held West Germany more or less from 1969 to 1982; they were less willing to buy expensive American fighters than the CDU would've been. (I won't put spectrum labels on them, because those differ so much globally, but the CDU is the more conservative of the two.) An SPD government is definitely not buying a pure fighter.
It's hard for me to say how this might've impacted Tornado or Eurofighter. Since the F-15 is significantly more capable than the F-4, they really would have had a fighter (provided it could drop bombs) that could carry them through the end of the Cold War and even up to the present day. That could save the government a whole lot of money. On the other hand, it would mean West German, later German, businesses wouldn't get to develop and build fighters of their own.
One last thing, though it's an F-4F thing. Deleting the ability to use the AIM-7 Sparrow, regardless of its poor performance in Vietnam, sounds like a very bad idea. I don't know the reason for it. If they would have done the same thing with the F-15, there is much less of a point in having F-15s.