Personally, I think it might mean the successor project (next gen nuclear subs) gets the axe.
Too late for that. The Astute programme is already well under way. The first two have already been launched and construction on a further two is already well under way. Worst case scenario will see the Trafalgar class being kept in service a little bit longer.
If you are talking about replacements for the bomber subs, its already been established that they will be replaced come hell or high water (even the lib dems have acceded to this)...