None of it's worth the bother, to be honest.
The simple answers are that I don't think arena costs are in any significant way responsible for users leaving the game. Heck, the stupid back and forth we're having probably is more likely to drive people away if it persists than arena costs ever will. Larger economic issues, sure, game balance issues, absolutely. Some arbitrary two year deadline to "complete" an arena, depending on the definition of "complete" in play at that time? That's almost certainly inconsequential, as a review of the threads in the suggestions/help/global forums would suggest - there's simply nothing to substantiate that there is a groundswell of people who get frustrated at the cost of building an arena.
Anyway, enjoy the last word. This is going nowhere, and we could either spend another hundred posts going nowhere without grace, or I can just walk away. I like that option better.