Yep, the lockdowns are untenable, which is essentially what the Imperial study concluded too when it said that "We do not consider the ethical or economic implications of either strategy here, except to note that there is no easy policy decision to be made." It's not geared towards what is economically realistic. It just says that given unlimited resources and no corresponding risks, such and such might be the best course of action. As such it's just one more input for people making decisions, and it has to be weighed against estimates of a thousand other risks and costs. The entire world economy is literally going to tank if you try to maintain the measures that some countries have instated, and that's going to cost a shitload of lives through other causes in return.
It'll be interesting to see how the world reacts over the next few months. Spontaneously my gut feeling is that all the rescue money should go straight into healthcare, food and people (governments starting to pay citizens directly to maintaining social distancing might be a good idea), not to bailing out things like airlines and Wall Street who won't survive anyway since this is going to drag on for a very long time, but it's strictly my amateurish opinion.
von der Leyen claimed today that a vaccine might be available already this fall, but most experts seem to think that's extremely unlikely.
