I reckon Haaland will move in the next 24 months and will move to England. I personally do not see him staying in Germany (i.e. Bayern; surely Dortmund said the his clause would excuse another German team?) Or Spain, as being Nordic and having some experience of living in England, it should be his best bet. Further, his playing style is suited to Northern European football.
When he does leave Dortmund, I reckon every club will make a play. This is how I see it:
Liverpool - I do not actually see him going here. Reason for this is Klopp and their squad make up and their style. First, I reckon Klopp will only stay with the Dippers for another 2-3 years. He doesn't strike me as someone who will stay at Liverpool for another 5+ years. This will mean they go through a transitional period. Further, their squad make up means they are in their peak as of now. In two years time, they will be at the tail end of this or past it (Mane, Firmino, Salah, Henderson, Thiago, VVD, Alisson, Fabinho) will all be 30+. Ok, Jota is looking promising but they will need a serious overhaul at the end of 2022/23 season. Further, they have a very fluid system which isn't really his style as wants to essentially stay in a No.9 role the whole time. Personally, unless Klopp stays and they pull another three Jota's out of the hat (and he can continue on his current trajectory) I do not see him going there.
Man City - They have similar problems in the management department and squad demographics. However, they do have owners that can blow everyone out of the water and will spend to overhaul the squad to a significant level. Further, his father played here so he has some attachment to the club. I would have them as favourites unless something drastic happens in the next 18-24 months.
Man Utd - Lets be honest, the club must look like a bit of a basket case to everyone on the outside. Further, his fat cnut agent isn't exactly the fondest of the club and if CL isn't secured next year the club could get a yo-yo reputation for being in and out of the CL. If finances/building his brand is his biggest objective then sure it may happen, however of the Top 4, I would have Utd last, especially as the club needs to overhaul defence and midfield before it gets to the forward line.
Chelsea - Personally, I have them second after City but it will depend on how they develop over the course of the next 18-24 months. By 2022, they could very well have the best squad in regards to age demographics and balance as by this stage their squad will read: Chilwell - 26, James - 22, Pulisic - 23, Werner - 26, Mount - 23 Harvetz - 23, CHO - 22, Zouma - 27/28. In my opinion, they will also add Rice in the next 12 months, who will only be 24 in 2022. This is also before they get to Amapdu (who has been very good for Sheffield Utd this season - 23 in 2022), Gallagher - 22 in 2022, Gilmour - 21 in 2022 and Sarr - 23 in 2022. The only players in the first XI who would be getting to the wrong side of 30 would be Ziyech - 29 in 2022 and Mendy - 30 in 2022. Their squad filler will also be something like - Abraham - 25 in 2022, Azpi - 33 in 2022, Tomori - 25 in 2022. For me, unless they go off the rails in terms of development (or Abraham becomes a world beater), they would probably be his best fit. However, I think City would still be his preference.
Tottenham - Cannot see them competing with the above four owing to their lack of trophies. I can see them winning a few things in the next two years, as it is what Jose does, however I do not think it will be enough and at best they would appear a sideways step from Dortmund.
Le Arse - Have the worst age demographics of all the six sides listed. Cannot see them being a serious contender.