No all remaining classes in Players Handbook have equally chance to be released.
Yes they do ... and that chance is 100% ...
That was one of first promises Larian give us, that game will certainly include ALL RACES, CLASSES AND SUB-CLASSES FROM PLAYERS HANDBOOK.

So ... i presume its quite obvious.
We're 5 classes short of the full roster. All the classes will be there, thats not a concern. The subclasses on the other hand could be considered a problem, seeing as they have not yet properly addressed the Wizard class in general with the learnable spells issue. Wizards have 8 different subclasses. Clerics have 7... and thats just the PHB. I seriously doubt they will be able to implement all of them to work as intended, some will be there only in the roleplay sense. And then we could talk about the deity options, which is severly lacking, both in choice and the impact to the story and/or dialogue. The addition of the Paladin class would have to address those issues as well.
And the races... well, what we currently have is a lot of options but there is still much to be added and implemented to satisfy the PHB roster.
+ Dwarf (missing only the Duergar)
+ Halfling (missing only the Ghostwise)
+ Tiefling (missing Baalzebul, Fierna, Levistus, Glasya, Dispater and Mammon heritage)
+ Missing:
Half-Orcs,
Dragonborn (they should have 10 available dragon ancestors to choose from) and
Gnomes (which will need to have Forest, Rock and Deep gnome subraces)
+ The Gith, although not a PHB race - but still in the game, are also missing a subrace (Githzerai)
Anything more than that will be a bonus. Theres a book in the druids grove that serves as a sort of a tease for the Aarakocra, Tabaxi, Tortle and Genasi races which aren't the most common of sights on the road to Baldurs Gate, although I would love to see them in the finished product along with a few others (the subraces for elves in the form of the Eladrin and Shadar-Kai, the Aasimar race, the Vedalken), I'm not going to hold my breath.
Larian has A LOT of work ahead of them still. I hope they will pleasantly surprise us when the full release rolls out, but I fear that some of the designs will go wrong.