Alton Towers should be pushing to have everything open for next weekend with the exception of Galactica and the two rides which are being removed.
Without wishing to bang an old drum to repetitively, the Smiler incident was less than a year ago and the media are going to be watching the opening with interest. When, and it isn't if, but when, there are floods of complaints when NST, Hex, Ripsaw, Flume and Charlie aren't open, the media will lap it up creating links between the closures and loss of income due to the incident last year.
Alton need to be pushing the 'business as normal' mantra as far as is possible, which is presumably why they've been so keen to get the Smiler reopened for the 19th.
Not only that, but temporary bookings or season pass renewals off the back of rides being open which will in fact be closed, is going to result in a negative stigma surrounding the park overall.
The other point is that this leaves almost zero room for error, if the reported closures are accurate, what happens if the mine train or thirteen breaks down? There is almost nothing for the middle of the range ride market, leaving just coasters pretty much.
If, as suggested above, whatever work needs to be done really can't wait, then the only real solution seems to be repairing individually.
Admittedly my knowledge of the inner workings of the theme park industry are limited, but it is very difficult to find grounds to justify closures for this length of time. Loss of income doesn't really cut it, there was a whole new hotel built last year.
Hopefully, as said previously, the information was either inaccurate originally or has been rethought.