It might happen, but it looks like there is going to be a little rash of undisputed champions over the next few years. If that happens it will be bad for Taylor, Crawford, and Usyk (assuming he doesn't beat AJ and go on a run of 5-10 big wins at HW). I'm just not sure the opponents will be there for Taylor to be remembered as an ATG unless he can succeed all the way up to MW or something. Ultimately, history seems to remember the ones who were in fights that were huge events and worth rewatching years later and tends not to correct for bad decisions. I think Pac, AJ or the winner of AJ/Fury if it happens, Canelo probably, not sure who else. I'm just thinking about who will be considered ATG, not who should be.
Chocolatito and Canelo. Newer than these guys don't fight enough. They don't care about that, anyway. They just want money and to be the flavor of the week on social media.
Assuming there is no dispute Pac is already there: Canelo Lomachenko Inoue Gonzalez Fury Honorable mention: Donaire
Is Pacquiao a current fighter? If so then Golovkin, Canelo, Pacquiao, Usyk and ... somebody else? Maybe?