As I've said before, I feel the reason the game is only 55% complete and still took 8 years to make was largely because the team pulled an FFXII and had to build a completely new engine to get what Nomura wanted. Tabata saying they wouldn't work on implementing anything new mainly means that even if someone came up with a cool new idea at this point, it won't make it into the final game because it would take too long to figure out how to program it.

Back when Versus XIII was first announced Nomura was talking about making the cities fully explorable with your characters able to enter every building with NPCs and various rooms as well as seamless gameplay change with Noctis being theoretically capable of switching from an action game mechanic to a FPS one on the fly and this was still before anyone knew the PS3 was a kind of a bitch to program for. I'm pretty sure this got toned down and even though the PS4 could potentially make some of these ideas come to fruition, the fact it took them 8 years to get to this point means the team is done with trying to expand the scope of the game, which is why I feel Tabata said that. The finalized what they wanted the game to be and they are sticking to it instead of trying to throw every bell and whistle they dreamed up in pre-production into it while also trying to finish the game. Its been almost a decade, SE needs to cut their losses and build the best game they can with what they have developed so far.

I am not concerned about Nomura stepping down, especially since it had more to do with getting him back to work on other projects he's put on hold for XV as opposed to being removed because he's a lousy director, most interviews I've read say the story, characters, and game structure are still Nomura's ideas, Tabata is just seeing them to completion. It sounds to me that the software has been finalized and they chose someone familiar with the hardware, so 55% completion is probably not as bad as it sounds since he'll be able to make the team build the game pretty smoothly. Of anything, we should be happy Tabata was honest enough to seriously give real answers to the questions fans have been asking for awhile. I find it amusing that it's the new comers Tabata and Yoshi-P who are being more up front and frank about their projects as opposed to the old guard of Nomura, Kitase, and Toriyama.