My suggestion about this game doesn't seem so strange, and maybe BB is even dealing with this as I type this... (because there's a titanium/ granite search in the geologists menu) Anyways wanted to share my idea with you guys.
I was thinking about another small island added to the current home island. This new island would hold let's say 2 new sectors with hardcore bosses and should be accessible at let's say lvl 45/50... Once defeated, this new island would hold 2-3 titanium and granite deposits which can be found with the regular geologist. It could be accessible via a bridge or maybe a harbour we'd have to build to reach the island...
I made a little example:
I know you guys may think "there has to be a challenge", but it still would be as these bosses would be very hard and cost a lot of troops and other stuff perhaps. You could even make a quest that you have to finish to access the island... Just an idea of mine :P What do you think?
grtz, Satrax