Well you can still fly to the islands. Its just that things like insurance might work differently (or not at all).
The crazy thing is that Thessaloniki has been quite a hotspot too, definitely more than some of the islands (though not sure how it compares to Crete).
Personally I'm not very familiar with the city... but I do know that it is well known for its cuisine. Probably very different from the island style that you were hoping to find, but hopefully good/nice nonetheless.