I am not an epidemiologist, but as I understand it, areas that have already been hit hard are more likely to see a second wave that is less serious and slower-developing, since large chunks of the population will no longer be susceptible. But it also sounds like, from what people are saying, it's unlikely we have had anywhere near the proportion of the population exposed that would need to be to count on any sort of herd immunity to protect us from that second wave.
Long story short, I'd guess that if we lift restrictions too much, we'll eventually discover a need to tighten them again until we find sort of a balance that allows life to resume at some acceptable level while also keeping exposure to a minimum. I wouldn't be surprised, for example, to hear that 24-hour grocery stores remain on limited hours well into next year, so that they can continue the enhanced sanitation procedures they've implemented. We might also be eventually looking at bars and restaurants limiting their on-premise guests to numbers well below those set out by the fire mashall.
All I know is what I’ve read in the last month but the second wave of the 1918 flu pandemic was far more deadly than the first. I may have posted this before but it’s a very good read:
https://www.smithsonianmag.com/history/journal-plague-year-180965222/