East Stand and Corners

All this talk of the West Stand Arch going up later this week has got me thinking about the future of the East Stand Arch.
I was told on a recent visit that if (when?) we move up the leagues that the four corners will be filled with seats and the East Stand will become a two tier stand - increasing the capacity to somewhere around 32,000.
Does this mean that to put up the second tier the arch would need to be taken down (and presumably placed onto the pitch during pre season) or is there already enough room under the existing roof to accommodate the second tier.

If a decision is taken to increase capacity and we were able to obtain planning consent that could be done without removing any roof or arch.