Getting back on topic re Jetstar. The companies QF owns less than 49% of, I can see them exiting (Jetstar Pacific, Jetstar Japan, etc). As for Jetstar NZ, there's also a good chance of JQ exiting that and transferring those aircraft back to Australian Domestic/Trans-Tasman runs. JQ has already exited regional NZ operations and transferred those aircraft back to QFLink.
Assuming that SIA doesn't have a 4th attempt at the Australian domestic market, I could see QF exiting 3K (Jetstar Asia) being a possibility by selling their 49% stake to another company.
Either way, JQi in Australia is a good chance of being decimated if not folded up entirely. A post COVID-19 JQ-i could have their international flying reduced to just Trans-Tasman, Fiji and Bali "bogan-bus" flying with A320neos and A321LRs, whilst exiting long-haul completely with the 788 fleet transferred to QF mainline.