You can't test a vaccine without someone who has the virus and you can't attain or even test herd immunity when it isn't prevalent in a community. So really whilst virus cases coming down is good news, it's very bad news if we want a vaccine or some immunity from the virus.
It's horrendous but we have to resign ourselves to two possible scenarios:
1) We learn how to control the spread (following social distancing and contact tracing) and the virus slowly dies out over a number of years but it maybe becomes a repeating flu type illness that infects and kills X number of people per year.
2) We see a second wave, a third wave, a fourth wave, etc etc and we continually go round the houses until a vaccine/herd immunity is developed.
Either way, neither of these options are good because option 1) means years of misery and option 2) means a lot of deaths and misery.