Seasonal flu strains are predicted in advance by studying the evolution of strains, and by seeing what happens in regions which experience winter at the opposite time of year to us.
Pandemic flu strains dont offer the same opportunities. To create a pandemic in the first place they have to be 'novel', different enough to existing seasonal strains to make our existing immunity, and existing vaccines, ineffective.
Only if we were correctly able to identify a flu strain in animals quite far in advance of that strain spreading well in humans, might we be able to have a traditional flu vaccine ready in time. Or, if work on more generalised flu vaccines that arent so strain-specific advances int he years to come and offers us a more universal solution.
There are still a number of reasons why the reaction to a new flu pandemic might not resemble this covid pandemic. These include:
If flu antivirals offer some protection or treatment pathway. Even if they arent brilliant, these offer governments a way to reassure people and to be seen to be doing something.
If the hospitalisation rate, age profile of the most vulnerable etc etc seems within the bounds of what our systems can cope with.
Other societal attitudes and expectations, and patterns of response seen globally. The last pandemic has upset the apple cart in terms of what cold calculations the establishment think people will put up with, but there is only so far I can run with this idea, I cannot make strong predictions about the next one. It is unfortunate that so many people got burnt out by the pandemic, and wont engage with these sorts of topics in the way they would at the height of lockdowns. For example a society might want to have more frank and honest discussions about what level of funding and spare capacity we put into health services, what level of 'population triage' (leaving some people to die in a pandemic) is deemed acceptable, etc etc. But this sort of stuff does also tie back into an earlier point - if authorities are able to point to medical, pharmaceutical interventions that can help, this is expected to have an impact on what other, non-pharmaceutical responses people think are necessary. There were people here who were understandably looking to buy into reassurances in the early months, given half the chance. If I run with that idea then it would not surprise me if the presence of antivirals that could do something, anything, would be good enough for some people, even if such treatments still left plenty of people vulnerable. Our governments traditional comfort zone in the past certainly involved throwing large quantities of tamiflu at people, including using it as a prophylactic during swine flu despite other countries scratching their heads about that untested use of that drug for that purpose. Even if I turn down my level of cynicism a bit I'd still say that traditionally the UK establishment loves that sort of thing, they find it a much easier sell to get people to 'keep calm and carry on' if they can claim to have some medical weapons in their arsenal, never mind quite how effective those medicines are.