I have a cruise booked for August that was rebooked from May--though a lot went into that decision, including expiring airline travel funds, the WDW free dining rebooking offer etc., and if I was starting for scratch I don't think I'd book a new cruise then. Even setting aside the risk of Covid, I think that there are some operational downsides to sailing in August. For one thing, there may be enhanced preventative measures that could interfere with cruise enjoyment, like closed pools, no face character interactions, no pirate party etc. There is also a increased risk the whole ship may be confined to rooms if there is positive case on the ship. And risks of being quarantined upon return, which could have varying consequences depending on policies of employers.