MOAR SPOILERS! This time for next year's new era of Doctor Who because there have been more casting announcements and they're... interesting. Not good or bad as yet but interesting. More under the photo.
Actually its been thirty-five years now I think about it. The last time there were four in the TARDIS was the Fifth Doctor, Tegan, Nyssa and Adric. So basically I'm looking forward to seeing what can be done with a crew that size under a vaguely competent writing team.
For reference since we don't know who aside from Chibnall is writing this series: any modern writing team, compared to rambling incompetence of Season Nineteen, would be seen as competent. The Master was wearing the corpse of one of the companions as a skinsuit and somehow this failed to come up in the season finale when the two characters met multiple times. They killed a companion and consciously chose the one nobody liked and still gave the episode silent credits.
And that was probably the best written of Davison's three seasons.
But, yes, four regulars. Potentially a bit crowded given the length of modern episodes but seeing how it didn't work too badly in any River episode from Matt Smith's first two and a bit seasons there's more than enough reason to hope. Also, Bradley Walsh will be the oldest companion ever (actor-wise, because obviously Romana...) and I am interested in what that's going to bring to the role.