Playing without benzema gave very big impact on the club. That proves that if benzema has the biggest contribution to the real madrid last season. Joselu's level is far below benzema at this moment.
Madrid shall have added new striker on its line up. The club can't only have joselu as pure centre forward. Joselu's performance in pre season was so bad.
Madrid's current advantage is in their strong midfield. but as you said their weakness is on the right wing of defence. maybe Ancelotti will make some rotations in defense to find some balance in the Madrid team.
Meanwhile, on the front lines, the loss of Benzema in the team was felt. even that was seen last season when Benzema was unable to play. Rodrygo, Vicius, and Joselu seem to have not satisfied Ancelotti. Madrid will have to find the right formation to push Joselu or Rodrygo further forward if they don't find cutting-edge attacking options this summer.
but I'd rather see the combination of Rodrygo and Vinicius upfront than Joselu there.