If he really goes to premier league, we are going to see a whole another series of ronaldo vs messi type of deal in our life time and that would be awesome. Back in the day Ronaldo and Messi played in the same league for many seasons, and that gave us a lot of competition, if Mbappe leaves for any team in premier league, that would mean Haaland and Mbappe would be playing against each other and that would be a great thing as well.
Mbappe does not have to move to Premier League to make another dual competition with Haaland. Of course it would be more interesting if they play in a same league but it is still fine if they play at different leagues. They can compete each other with total goals, assists, titles in their national leagues, Champions League and Ballon D'or.
With Mbappe bad behaviour in last several months, I see Haaland is taking a lead and if Mbappe continues like this, he will lose against Haaland. His playing style relies so much on his speed and if he wastes his young ages, he will never be able to catch Haaland.
We saw how Gareth Bale lost his best form and performance just after a few injuries. I don't expect injuries for Mbappe because watching him is interesting but injuries in sports are unavoidable and Mbappe simply is not excluded from injuries.
In this situation, Haaland has Pep as well, which is a good coincidence for the same reasons, but Mbappe won't have mourinho I assume. It is going to be a great transfer if it happens, but I still expect it to not happen to be fair.
Mbappe does not want to be managed by Mourinho because Mourinho does not support such undisciplined and unprofessional responses like Mbappe usually does. Mbappe can join Chelsea that is a club usually support players rather than their coaches.