I think we will have to wait for a/the budget for the official confirmation of what the rates will be - back to the bad old days of hmrc and 3rd party software providers having no time to practicably implement whatever the flavour of the day new change is for the current chancellor. It's easy to bring these new flavours in harder to get rid of em.
In the meantime lets have a guessing game.
My estimate for primary threshold 2020/21 is £9,500. As a tie breaker lets go for a long shot estimate for secondary threshold 2020/201 of £8,840. That would probably be a recent record difference between the two thresholds for those who like their allowances stats.
Oh well at least the personal allowance doesn't end in a 5 anymore unless our current chancellor really wants to may me mad this year