Even after his 1 year contract currently in Madrid, we will still get to see clubs willing to have him likely the Saudi league. Modric is a great player even when he would turn 40 I believe he can still make a good game on the pitch. Can't wait to see him deliver those passes to Mbappe, it will be a lot fun to watch how Madrid will conquer clubs with ease following the combo between the long passes from Modric and an excellent finish from Mbappe. I know Modric won't be played whole 90mins, Valverde should use this time to master the work of art by Modric so he can do better in his absence.
Going to Saudi should be for retirement and not to continue his career. At age 40 it is advisable to not continue playing football. The idea, intelligence, and technical know-how will still be there but the strength to do a lot of things they could do at a young age won't be there anymore. Modric can do well in the pitch at age 40 if he has a young talented midfielder pairing with him so that he can easily give instructions and control the midfielder without getting to do much work running around. It could be that he directed a true pass or countering attack pass.