While I think crypto in general, and blockchain ledgers more generally, will remain hot, and the others mentioned in poll too, I voted "other". I think the following will get a lot of attention...
(a)
Internet of Things (IoThings) and the general idea of connected devices of all kinds. Clever names in good extensions, or brandable, will find customers. Both .com and .io will be good in these, and some of the country codes. I think words directly IoT, IoThings, InternetOfThings will sell of course, but even more so ideas that use connected or synonyms in a clever and memorable way.
(b)
Nanomaterials While nanotech and nanomaterials have been around for years, I think many of the most exciting things, in particular building really tiny and smart nanodevices for things like medicine, will begin to take off. More than just experts will begin to combine these two ideas in an Internet of Nanoscale Things. I think that while .com will dominate, .io will be very popular in this area, and there will be occasional interest in a few of the new gTLDs.
(c)
Genetic Medicine Both in terms of editing to cure or prevent genetic related diseases using things like CRISPR, and genetics broadly and generally (e.g. consumer things like the ancestry services). I think there will not be a huge number of sales, but some of them will be at very good prices.
(d)
Psychology/Healthy Mind While always popular, it seems to me interest in these areas keep growing. I don't see this as something that sells in $$$$$ or even $$$$ much, but a lot of small practices, authors, speakers, bloggers, etc. will pick up $$ to high $$$ domain names in this area. Probably room for some of the new gTLD to have an impact here too.
(e)
Design. I think design of various kinds will be popular, selling at amounts ranging fro $$ (one person starting up wanting a presence) to $$$$$ or more. It is encouraging that big names like NPR, Facebook and Kohler have used the .design TLD, and I see this helping get others online. Most sales will be in .com, but I think .design and .ink may be the unheralded winners among a year that in general will show little growth in the new TLD.
Best of luck to everyone this year!
Disclosure: I have interest in all of these areas and they are part in my portfolio (www.namesthat.win). However, I tried to be objective in writing this.
Bob