Yeah, that’s the issue, ideally you’d go for a ground mid distance to make it ok for fans but Villa Park is only 42k. They’re doing a new north stand though which will take capacity to 50K so brings in into play. But the big / appropriate stadiums are either in London (Spurs and Arsenal) or Manchester/Liverpool. Newcastle and Sunderland kind of out due to location.
whether clubs would want to host semi finals these days could also be an issue, I suppose.