The answer to most of the "could we" "can we" questions is probably "Yes". If there were the will. The real question is "Do we really want to?"
To mind mind, "No". Because there is neither the will nor the need. As the UK is at a position where could build an entire new system it was a good time to raise the issue. It will now be for the Government to cost the options and decide the capability (and its inherent security) that wants to own and to pay for. An expensive ballistic option with a small fleet of submarines and all the support, storage and maintenance issues (especially if Scotland keeps being pissy) or a smaller, less cryptic, airborne option.
I wonder if there will be anything about it in the SDSR. There ought to be. Or will there be an MPs' rebellion that decides they don't want any of it?