I'd be happy to see a PLOG happen (in Sorrento!), and to help organize it.
And the few voices I've heard about it in Barcelona raised some concerns, which I think we should address at the same time as we are discussing the theme of a tentative PLOG 2018. My take on those concerns is that they are centered around the overall calendar of Plone sprints and events in 2018, namely that there are already two events planned for the first quarter of the year, i.e. the Innsbruck sprint and the Berlin Plone Tagung, unless I'm forgetting others. I know there are also some React and Angular conferences in Europe in the first and second quarter, which some people plan to attend.
Typically, the Hotel Mediterraneo extends their special rate to us in the week after Easter, which next year falls on April 1st. In this scenario, PLOG would be from April 3rd to 6th (Tue - Fri). Of course, we should check with the Hotel whether this assumption is correct.
I think we need to get a rough headcount of people planning to attend, or definitely not attending as a first priority.
As for the topic, I think Pastanaga might reach a pretty solid state by then and could be the galvanizing force all other aspects of our headless story really need. It could also be a strong piece of plone.io.