I can absolutely see it happening. It'll cost as much if not more to make current OT anything like what a new stadium could be.
And before anyone says it, we'd all be gutted when the current ground comes down. It's been home for 113 years, it's hard not to be gutted.
Times change though, I'm sure the same type of people said the same thing about Bank Street or North Road.
It's not the building that makes the memories, it's the games and the teams and the players and the managers and the atmosphere that we remember. We can create the exact same thing in a new ground if designed right and I have huge faith in current stadium designers to create something that pays homage and respect to the current ground and to the history of the club and city/surrounding area but gives us a platform to really be world leading on a matchday. The way stadium design has gone over the last decade or so is really something to behold, it won't just be a soulless, boring, cookie cutter ground I'm sure of it.
We have to move away from the railway line because it's not going anywhere and will forever be prohibitive to us. It turns a simple revamp into something much more expensive and complicated. We've got the space to built on the same plot of land, our postcode wouldn't even have to change, it'd still be Old Trafford and few teams have the luxury of that.