Don't Wait If You Want a Headphone Jack
If you want a 3.5mm headphone jack on your next tablet, you'll probably want to go with another line of tablets.
Last year, Apple killed off the 3.5mm headphone jack on the iPad Pro line to make space for internal components. If you buy a 2018 iPad Pro you'll have to rely on wireless headphones or purchase a USB C headphone adapter.
At this juncture, don't expect Apple to bring add a 3.5mm headphone jack to the designs of future iPad Pro models.
Both of these models come with one.