I would think it pretty much goes without saying that there is nothing worse than +/= awaiting Black in the Tartakower, and that a better question would be whether in fact anything like a definite +/= has been established.  A few observations:  two encyclopedias from the late '90s thought White had a (narrow) route to +/=, but three of them published between 2003 and 2008 thought the best-play lines should be equal or unclear or the like, rather than +/=.  Ivan Sokolov's discussion of various lines in his 2008/2009 book also seemed to fall on the "equal with best play" side.   

The Tartakower's theoretical status is pretty good.  I don't think there's anything worse than +/= waiting for Black, and he generally gets some counterplay in an uneven position.  It will probably make a comeback at some point (as the Lasker has, a little bit, being used by Anand and Carlsen).

There are reasons why it might not, however.  White has a very comfortable position which could be characterised as "easier to play", and the Tartakower is positionally dangerous for black; if he gets tied down the hanging pawns can be very vulnerable in the main theoretical lines, for instance.

It just isn't terribly attractive even if it is okay, and you have a broad preparation spectrum playing 1...d5, 2...e6, including the Catalan (very popular for White right now), Exchange (also presenting problems for Black), and several different versions of Queenside castling or Bc1-f4 ideas that avoid the Tartakower entirely.

For a full comeback, I think A. White needs to prove something in the Lasker and other main lines of the Bg5 QGD, and B. Black needs to patch up the Exchange and Catalan enough to make them less enticing.

Hi friends: I did a review of the Tartakower D58 in my data base of more than 3 million games. I put an ELO of 2000 to 2500 and it gives the following: 1-0 30%-- 1/2  52%-- 0-1 18% . It has been used for Kasparov, Karpov, Anand in his last game of the World Championship, Short etc. But it seems is not good anymore. Everyone plays slav, semislav... what has happened with the trusty and old Tartakower. Why is not in the repertoire of the Top Guns As it was in the arsenal os Spassky, Nigel Short, Karpov? I would like to hear your opinions.