Let's forget about his age, Joselu is a good player but you guys forget something about how Ancelotti has been rotating his players. Since before now when Madrid hasn't gotten Mbappe let's say since the beginning of last campaign, has the coach been showing any sign of giving this guy Joselu a better opportunity? He always sit on the bench or sometimes he plays Joselu around 80-85mins just for him to kill the time, sometimes Ancelotti doesn't even play the guy so what's the assurance that he'll have a playing time (base on swapping the playing) now that they have Mbappe? To me Joselu is just there and there's no special reason for him to be there, if Ancelotti wants to do any sub he can even bring in a defender or a midfielder instead of Joselu.
Ancelotti did not give him a chance to start even after his goals in the semi-final against Bayern, so it can be said that Ancelotti is not changing his working strategy and there will always be a place for Joselu on the bench. Moreover, with the arrival of Mbappe, this situation will worsen, I doubt that Mbappe or Rodrigo will be on the bench. But apparently Joselu is happy with this, he goes on the field for twenty minutes, scores several goals, but he plays in Real Madrid, everyone makes their own choice.
The last news I read was the option to make Joselu permanent until June 30 to activate the clause. After that, I haven't received the latest news regarding this 34 year old player. IMO, Madrid or Ancelotti still need a pure striker and Joselu is that option. Even though it looks like Joselu won't have much playing time, it seems that staying at Madrid is the highest point of his career at his current age. However, he can still contribute to Los Blancos. Even though he was only a cover player, Joselu made a big contribution, especially when they overthrew Bayern Munich in the Champions League semi-finals.
Well, as you said, it seems very likely that Joselu would be very happy if Real Madrid made him permanent at the Santiago Bernabeu. Even though there is now Mbappe, who will most likely always be the main starter in Ancelotti's squad, this apparently does not prevent Joselu from remaining at the Santiago Bernabeu. After all, his role will be quite crucial as a substitute player with the schedule that Madrid will carry out in the new season. Another option, Ancelotti can use various systems and strategies according to what he wants to implement for his team's squad with the available player resources. By the way, I am quite sure of the previous news, that Joselu will enjoy his role at Real Madrid and that is his wish and decision.