There won't be any big improvements in the game anymore, those few veterans need a new challenge with new levels, new jobs,...
I don't think there are too many new players in the game, and they should go to the newer worlds. Active players in the old worlds should't be held back because of them.
It's not good that someone who has only been playing for a few months or only 1 year is almost equivalent to someone who has been playing for many many years. Or why should we compare a player who doesn't log in every day, or just sets up a few hours of work, or maybe just goes up to the ff and do nothing else... with a player who is constantly active, acquiring and upgrading the latest sets, even buying them for nuggets, or do 1000 jobs/day...
Anyone who is even slightly active has already reached the 150 level.
A 150 level player gets 13 million XP a year just by logging in. So, 3 years after reaching level 150, a player will have around 60-70 million XP at least. (22+3*13) But a moderately active veteran player is around 100 million XP, while a more active veteran player can reach 150 million XP. Above them are the XP-hunting players, but they are not many.
70 million XP would take us to level 165, 100 million XP would take us to level 172.. this is not a big difference.
It is pointless to raise only to level 180, because some of the players will reach it immediately, other players will reach it within 1 year thanks to the sign-in bonuses. So, a good number of active veteran players won't have a challenge soon. It will be easier to level up because the jobs will give more XP. (and I hope FF, duels and quest too)
It is not realistic that someone who has been building a church for 5 years turns into a dueller or fort fighter after raising the levels. Maybe try it for a while, but that's not what he was interested in the game so far, so don't be afraid of a few high-level players.