Thill became the youngest capped player in Luxembourg history when he made his debut on March 25th of this year in their 3-0 loss to Bosnia-Herzegovina. His people meet with Bayern in Portugal last week when Bayern played Lisabon where the two sides agreed to a 3 year deal, though nothing has been officially signed. He has garnered significant interest from AC Milan and 1899 Hoffenheim, along with several clubs from England, but apparently he's made up his mind, choosing the Rekordmeister very early on in the process.
The only question that remains is whether the 16-year-old will join Bayern this summer, in 2017, or in 2018, as he just signed a new contract at Metz in February of 2015. The contract, which he signed through 2018, has a player option for another two years until 2020. Bayern are ready to pay a transfer fee as high as €5 million, though they could get him for free in 2018 when the base years of the contract run out. Ultimately, though, it will be up to the club in regards to when they'll sell him.
Thill currently plays for the reserves of FC Metz and would join the U-19 side of Bayern until he turns 18 in February of 2018, at which point he would be eased into the first team. If he does end up moving for the rumored fee if €5 million, he would be the most expensive Luxembourgian player of all time.
The final contract could be signed as early as next week.