Will we be getting Series 13 & 14? Of course we will.

It was announced today that HBO have picked up all the series of Doctor Who since 2005, but the thing that is getting people excited is that they say they will also be getting three series yet to come - i.e. the forthcoming Series 12 plus two others.
Personally I don't see what the fuss is about, as Doctor Who celebrates its 60th Anniversary in 2023.
We know for a fact that we are going to be getting a series in 2020, and I find it inconceivable that the BBC would pull the show so close to that landmark event. If they were going to do it, then Series 12 would have to be the end, as going into 2021 - just 2 years shy of the anniversary - would be a terrible mistake.
A word of caution about the HBO announcement, though. All we got was a couple of lines in a statement - not the full contents of the contract. The exact wording might only specify that they have an option on Series 13 and 14, if they are made. It remains a very unusual practice for the BBC to commit so far ahead, being a publicly subsidised organisation which has to invest in programmes which people are likely to watch. If Series 12 were to bomb, they wouldn't necessarily commit to any more Doctor Who.
Something else which the HBO statement doesn't state is when the possible Series 13 and 14 might be delivered. For all we know Chibnall and the BBC have agreed a two yearly release schedule for the programme - so Series 13 might not be broadcast until 2022, with only an anniversary special in 2023, and Series 14 following in 2024. Alternatively, Series 14 might be split with half, with the first part in 2023 and the remainder in 2024 - after all, we only got half a season in the 50th Anniversary year. I'd be surprised if the BBC did celebrate the 60th anniversary by then taking the show off the air, so it must surely continue into 2024.
What shape the broadcast of future Doctor Who will take remains an uncertainty, but I do think that the proximity of the Diamond Jubilee makes its continued survival for at least a couple more seasons relatively assured.