I think the decision process is an individual one. No one knows what is going to happen in the next 4-6 months. However, what we do know
DCL reduced the PIF date to 30 days for the may cruises out of Barcelona (one of the european countries holding on to pretty strict covid travel rules). To me, thats an obvious indicator DCL isn't planning on releasing any covid protocols for the euro cruises until late march or early April. Unfortunately, If anyone wants to book alternate plans they need to booking those plans now, not in April. By April, summer accommodations/options will be drying or dried up.
Also, basing decisions on an assumption (that things will be better) may be viewed as risky by some. I personally see the cruise industry as the very last travel entity to abandon testing requirements...and amongst cruise lines, DCL will be the last to do so. The prudent thing is to base your decisions on the most recent information you have available. If you base your decisions on what DCL is currently doing and you're OK with that, then if they improve and you've decided to hang in, great! But if you are basing your decision on the hope that things will be better, but would otherwise bail if they dont improve, I would not bet on things improving at the risk of foreclosing on alternate vacation plans.
I booked my 12-day Mediterranean cruise on the first day I was able to last year. If I booked the same category today, I would have to spend at least $8,000 on top of what I booked it for last year. Im not sure DCL is planning on striking any "deals" on these euro cruises. Looks to be exactly the opposite, actually.