IMO the time jump will put them as HS seniors. as others have predicted.
For one this lines up with the actual age of the cast - at least.... closer to it. Finn Wolfhard is 19 as of right now so it's less of a stretch.
For another, closing the door on some ancient evil while they close the door on their HS careers/Hawkins/etc is just too good and too potentially satisfying to pass up. It almost writes itself - they play one final DnD campaign before going off to different colleges, etc.
For one this lines up with the actual age of the cast - at least.... closer to it. Finn Wolfhard is 19 as of right now so it's less of a stretch.
For another, closing the door on some ancient evil while they close the door on their HS careers/Hawkins/etc is just too good and too potentially satisfying to pass up. It almost writes itself - they play one final DnD campaign before going off to different colleges, etc.