It wouldent be unlimited, but I wonder if they could be made to last longer by changing the extraction rate and price? Make the mines/wells pull less resorces and raise the prices to compensate? No idea if thats possible or not though.
I wouldn't really want the resources to be unlimited. Maybe slow down the rate at which they are used up, though. Also, along those same lines, I wish the liquid resources (water and oil) would actually act like liquids. What I mean by that is that water gets used up directly under a water tower, but there is still lots of water surrounding that void. Why does the water surrounding it the void not drain into the void? I think a mod that would allow this to happen would be VERY useful.