Can't see how we could move it, if we could we'd have done it that way from the beginning, unless of course we knock down the north stand and play in 3/4 of the existing ground for a year.
Would never happen. Even more so because we'd be left with closer to half of the existing stadium than three quarters (phase 3 in pic below). No way that Spurs could or would stand for a season with a capacity of less than 30K, let alone less than 20K. By virtue of lost revenue, it would add a further £20 million or so to the cost of building the stadium.
The only way that building this stadium in one fell swoop could be achieved is if Spurs were to play elsewhere for a season or two.