Prediction:

1) People will be glad to see a PLD or WAR insteand of a DRK in any instance thats lvl 50 or lower.
2) Instance Servers will be fked over multiple times a day. 2.4 and 2.5 was bad enough and if they dont change the system we wont be running instances anytime soon until the 2nd or 3rd Emergency Maint :/
3) Ridiculous prices for new crafted gear/HQ materials - and i will make a shitton of money out of it
4) People will cry about stupid materia melding rates because they are too impatient and dont want to wait for tokens to build up
5) People will cry about the time it needs to hit 60, either its too fast or too slow. Even if they knew beforehand because Yoshi said its roughly the same as 1-50
6) People will cry about other people - because they do that always, even moreso now that they will have to run instances for EXP again.
7) People will cry about prices for Housing extension and Crafting
8) OK lets just end the 4-7 point list with: People will cry about everything that doesnt match 100% their expectations
9) FATE mobs will have like 7000% of the original HP, because 100+ people are hitting it like there wont be a tomorrow
10) Old Cities will be ghosttowns for the major parts and Ishgard will be laggier then mordhona on reset time at tuesday atm
11) People will complain about login times - i can see the AFK kick comming back, we all remember how bad it was at 2.0 release when we didnt have that feature yet

I could go on, over 18 month of XIV i been taught one thing: You never will please everyone

oh and: "We didnt expect that many players to be interested in XY" - DONT YOU KNOW HOW MANY ACTIVE ACCOUNTS YOU HAVE? Jesus <.<