They have to. Broad audience didn't care for the game at release, and it won't care one year after release without marketing, after Uncharted 4 and with a lot of other new games.

$40 with all DLC could do it. But I'm pretty sure it won't sell well anyway (better than the Xbox one version, of course, but that's too easy...).

ROTTR is now a $15 Steam sales game, that's basically it.

I bet the GOTY edition (or Ultimate Edition most likely) will release for all platforms at the same time.

why should they? it's your money, you buy whatever you want.

I fully expect that the PS4-version will be a so-called Complete Edition or GOTY-edition. As for PC if it is infact released in January they will get nothing extra

They obviously need to release it with all the DLC. Its unthinkable that they wouldnt.

I think that they got paid to make the other platforms wait... With or without more content, they will have to wait the time specified by the amout of money they received...
So, waiting that time its a decision made long ago, and I believe that even if they want to, they wont release the game anytime soon for PS4/PS3 or PC...

Maybe, but that would also say to the PS4 users "Hey, do you remember when we screwed you last year?". 

I think it's over for them. Next Holiday season, the basic PS4 SKU will surely be the Uncharted 4 Bundle (maybe even with the UC Collection in it?), with huge third party games like Final Fantasy, Mass Effect, maybe even Persona 5 and something like Destiny 2 (and the usual Assassin's Creed, CoD, Fifa...). And other first party games like Horizon and maybe The Last Guardian. The new PS4 users will get Uncharted in their bundle, the old PS4 users will have plenty of new and hyped games to buy, nobody will care about Tomb Raider, even with a Definitive Edition. Could be one of the first PS Plus AAA games, or like this year a huge discount after the initial fail in sales. 

I get you, but then I don't think Square/Crystal will do anything special to entice PS4 owners.

What I do expect though, is that, if there is a sequel to ROTTR, Square will focus on PS4 and PS4 owners and will do a lot of ass-kissing for the PS4 version. But I think the ROTTR situation is pretty much done by now on the eyes of Square and they will release the game on the other platforms and be done with it.

Yeah, seems like ROTTR can't catch a break from difficult release dates. I recall reading a rumor though, that said "exclusivity" of ROTTR was extended, which I don't believe, but then wouldn't surprise me if Square tries to push the PS4 release after the Holidays.

Doesn't Sony have a policy that forces the developer to add extra content in the PS version to make up for the delay when a game releases later on their console, or it can't be released at all? Maybe it will have a few more tombs and some new cutscenes. 

I remember reading something about that but can't remember where and how official it was.