First of all it will not matter as now mcu as decided to rebot all x men movies. After disney fox deal the old movies will not have any kind of effect in future

It doesn’t.
The old X-Men movies would have no impact on the MCU

Yes. There is impact of that mid-credit scene in mcu timeline but if your are asking if fox is still on it then here also multiverse will play major role. As he creates different timeline.

It would make no effect as Deadpool didn’t die in that scene as he can regenerate

No, it don’t have any impact of mid credit scene in mcu