A 10 year time skip would require the crew to get a whole new redesign, and doing something like that at story end guarantees that you are throwing money away from your merchandising and toys, you cant make new products and toys if the "advertising"(story) has ended, there would be no media out there pushing the stuff off the shelves.
Naruto merch did poorly and they tried to make Baruto to push the stuff but failed(except in JPN), dont even get me started on bleach they failed miserably the only thing Bleach had going for it is a game, and people have started watching Bleach globally more since end of 2018 that's why they are trying to cash in more with a new anime so they can use it to push more toys, merch and games.
Manga sales on average amount to 30% of total income with games, merch and toys making up 50% while movies and anime make up the rest, you cant sacrifice toys just so you can make your characters all grown up, it the same as burning money.
Look at Dragon Ball, they will never make Goten and Trunk grow up for as long as possible because they wont be able to get that toy money, i mean in the story they should be 15/16 but they still look 8 because of toys need to go.