It appears Greenland will join the USA either voluntarily or unfortunately by force (which would mean one nato country attacks another, and could end the nato alliance) as a territory or statehood. This will happen within 1 year from today and their zip code will start with 19000 USPS. 68% chance of accuracy.
Current residents will receive immediate citizenship and other perks (part of the deal) which could include private property payments/payoffs, relocation assistance, and awarded benefits of mainland citizens.
US Passports will be issued. They may be dual citizens of Denmark and the U.S.
If statehood they will be able to vote, electoral votes possibly 2-5.
Who to follow
