I was just wondering which sylesties are still due for a revamp, and how often they get revamped?

Lunemaras are slated for a revamp next. Ryories and possibly Bulbories are also going to have a revamp in a little while. I swear I saw a list somewhere earlier, but those are the ones I remember.

Theafy quoted this from Krin on chat a while ago (and put it on his user page!)...

"Bulbori, Faelora, Lighira, Lunemara, Lupora, Nytekrie will be the next 6 to be revamped (in no specific order)"

But note that each revamp takes many months, so there might only be a couple revamps a year... it's a long process!

Once a message is posted talking about an upcoming revamp, there is generally quite some time to prepare for it, give feedback on proposed artwork, etc. :)

For example, the puffadore revamp was announced in Sept 2016, and wasn't completed until Jan this year. The Lunemara revamp was announced in March and is still ongoing, etc. So you have plenty of warning before the next one!