Sadly, I think you are correct. I was actually pondering this one the other day when I realised that one of my favourite pieces of football trivia was about to change. (Hull City, by the way, is also the only club of the 92 that you can't colour any of its letter in.)
After Milton Keynes, I'd have thought other contenders for largest city never to have been represented by a top flight team would be Southend, Basingstoke and Gloucester...of which the latter two have not even been represented by league teams at all.
Bedford's got a population of 150,000 and never had a football league team, and having been relegated twice in two seasons to Southern Div 1 it's not looking likely.