I think the stadium is designed to have a 63,000 capacity when the upper tier is completed. To make it 84,000 would require a lot of work and a lot of money and is not feasible in my opinion.
I imagine it would be, at what cost is a big issue. Note as big an issue as we'd never sell it out and it'd be pointless. We'd struggle to sell 63000 most weeks even if successful
If we were as good and successful as Man City, would we have to extend the stadium all the way round? On the RR podcast, Murray said it can go to 66,000 quite easily and wouldn't be to expensive
Page down a few pages marra, this has just been discussed recently so you'll not get many responses to your first post. https://www.not606.com/threads/stadium-capacity.386261/unread