Any stadium, wherever it may or may not be built, would be modular and designed for relatively easy expansion. Brighton added over 8,000 seats after their first season at Falmer and this has become the norm in modern stadium construction. Well, not even modern stadia...Norwich found out that the foundations for their main stand were made to hold a three tier stand when they were laid back in the early 20th C.
One thing to ponder on is the cost of building a capacity that doesn't get used enough & the running costs to support that. Is it better to have a 25,000 capacity that gets sold out twice a season on a 22,500 average or build 30,000 to cover the occasional 28–29k gate?
I'd also be wary of Fisher-esque predictions on potential crowds in these rarified & heady times at the top of League 1 after 18 games of a 46 game season. Part of the reason for our current success is that we've finally started working within our means and are cutting our cloth accordingly. A return to the days where we had ideas of Arena 2000s, Operation Premierships or 7,000 going to Suxfields is a recipe for disaster. Surely we've learned our* lesson by now?
[* Our/we can mean owners, club, fans, whoever. Delete as applicable.]