By all accounts a particularly bad winter for flu is to be expected, and the NHS is already well behind in many other areas.
"Lock down for a couple of weeks to slow down the spread of flu to protect the NHS and save lives" is not beyond the realms of possibility.
Considering how accepting the general public has been lockdowns and curtailed freedom, i dont think its ridiculous to suggest that, with the right messaging, it could be done again in future.
Absolutely no chance is that happening with normal flu.
Even if they try it, it will not be adhered to.