I really think we're overdue for another mining expansion. That would **** quite a few birds with one stone:
1. Let us spend coins.
2. Let us use land pieces (many of us are maxed at 999 pieces, with nothing to do with them).
3. Give us more land space to put all those awesome new dragons and habitats on.
4. Give those who bought the last expansion and their right mine is closed a possibility to mine on that side again.
Really, that would be win-win all the way.