Yes we have community day, gold and glory, adventures... But what if we had some kind of new game modes? For example once a 3 months could arena return for a weekend or smaller amount of days, then leave and return in 3 months. This way it would not be dead at all...
Not just arena... There could be game modes like:
This game mode would be 3-4 maps with combination of riddles and the first ship that finds all clues where is the final chest and cashes it in will be winner.
Siren song of deep waters
Players would have to protect siren towers, but firstly they would need to claim siren with a special shanty. (It would take 15-20 seconds) Then they would protect it or claim other players towers and after the countdown ends (10-15 mins) the team that has most towers wins.