Not a virologist, but I don’t see how it could be too late.
This virus lives on human interaction. If it were possible to have no contact between people at all in a given country, the virus would die by the time those suffering right now are through being infectious. It might live on surfaces briefly, but that seems to be negligible for transmission. To be safe, you could extend the lockdown for a couple of additional days.
Now, of course it won’t ever be possible to pause all human contact. Older people have to be taken care of. Kids need their parents. Ambulances and hospitals can’t take a break. With families, it’s just maths. The household needs to stay separate from others until everyone in it would mathematically be through with the infection. I’m saying “would” because of asymptomatic carriers.
For essential workers, lockdowns do need to be supplemented by testing and all the precautions we’re currently taking.
I think that the problem, so far, has been timing and consistency. Timing in that it makes no sense to put a region under lockdown, but then allow free travel between its neighbor cities a few weeks later. You’ve just put the local population under extreme stress – for nothing.
Consistency in that there’d be ways to make lockdowns less traumatic and more effective. Grocery delivery, for example, is much safer than everyone congregating at the store. Kids shouldn’t have to slog through their ordinary schoolwork during lockdowns, but they do need emotional support and engaging projects that they, themselves, consider fun. Adults who are struggling also need support.
I think what’s needed is a giant volunteer effort and a lot of difficult decisions from the people in charge. I don’t think that giving up is an option.