Today another indication popped up that local elections are in the planning - probably starting with the Provincial Administrative Organizations. For 18 provinces the constituencies for a forthcoming election has been announced in the Royal Gazette, e.g. this announcement with the constituencies for Phuket province. These 18 provinces are mostly from the South, and some in the Central region. As I guess that if the local elections for the PAO will be done for the whole country, I expect there will be further announcements in the publishing queue - these 18 were already signed by the Election Commision in April.
Further local elections pending are for all the municipalities - these will also need constituencies defined first, as the current constituencies probably no longer fit with the population numbers. And of course there are many municipalities which were created or upgraded in the last 6 years. And also the TAO (subdistrict administrative organizations) need elections, though for these the constituencies are automatically defined by the boundaries of the administrative villages. And last not least Bangkok and Pattaya as special administrative units, as far as I know these two are the only which have a new governor/chairman assigned by the government.