The Paqueta thing seemed good as done but fell through.
Guimares and Paqueta are extremely close, Brazil internationals who share a midfield together.
The idea of them teaming up was likely very appealing to them.
Once Paqueta fell through, it became much harder to get Guimares to agitate for a move. Once Newcastle sorted their PSR concerns and didn't need to sell anymore, he became unwilling to move.
The club is likely looking at Musiala and Wirtz as long term targets that realistically cant be pried from their clubs until next summer.
Gundogan could be the perfect stopgap, a player who wouldn't need a long term commitment, who wouldn't need assurances of playing time, who fits the system perfectly.
They thought he was a one year guy at the time but the needs of the team are fluid and change constantly. A reunion seems to be the best case for the club at this present time. One more depth option really makes us that much more secure in the midfield.