There are already a fair number of people that think high-level play is not for them, even some that've never actually played at high level - they just remember prior editions they played breaking down and never being capable of reaching high-levels, so they no longer desire to try them.
The way to convince them with absolute certainty that they don't like high-level play? Demand that they build a character at 10th or 15th level with no played-out history in the campaign before that point, and then expect them to actually fully understand their character and their role in the game world.
My group and I, on the other hand, really like high-level play. We still don't start there, and I'm definitely not going to buy any adventure that is for high-level characters and not directly a continuation of something we've been playing through from low-level up to that point, because much of the charm of high-level play is the collection of various this-and-thats, and the culmination of character plans so that the high-level characters are something other than just the same low-level dungeon-crashers with higher numbers.
So no, I don't hope the next campaign book is 15-20 - I hopes it's no lower than 5-20, or that it doesn't bother with high-level content because I can spend a few minutes each week while running the published 1-10 portion figuring out where to go with the characters after that point.