Some kind of announcement will have to be made at 8 p.m. Thai time, which is 1300 GMT, because this is when royal news is usually broadcast. Even in the peculiar fairytale world of Thai royalism, it will be impossible for royal news to just ignore today's events. Something will have to be said.
It remains unknown what is going to be announced, but one point is clear — the announcement will mark the end of the reign of King Bhumibol Adulyadej, Rama IX of Thailand. There is a strong possibility that he has died. Alternatively, the announcement may proclaim that Bhumibol has abdicated and Vajiralongkorn is Rama X. The third possibility is that Vajiralongkorn is named regent. If this happens then technically Bhumibol is still king, but it is inconceivable that he will ever again play any role in Thai politics.