From Reddit: NO level sync when entering a dungeon with less that required players!

[Zebyxus]

It will most likely be available for Trials,as devs have said in an interview that Titan EX should become easier with new gear and levels in the expansion,as well as Trials being necessary for the main storyline.No news whether it will be available for Raids.Common sense indicates it will be available for everything except Savage Coils,since 1)finding a group of appropriate skill to do the content will become astronomically hard due to the content being obsolete and 2)a certain other MMO FFXIV gets pointers from's successful features is previous-expansion content being grindable by small groups/little effort required for glamor gear/mounts/pets/etc.

I can already hear people who went through the initial 'grind' for their ponies screaming about the injustice of it all... But in any event, should be interesting to see it in practice