As the title says. I'm solely interested in this for off-line play and have been waiting for improvements in that area. Any progress?
There were a few improvements, I'll sum them up:
reaching lv max (60) you gain prestige levels, each level up gives you a crystal, 5 are needed to buy a rift disk, which when opened gives 3 items at random, ensuring at least a rare one (think of it as lootboxes which can be bought only through ingame currency);
2) If you find old/broken/tattered piece of clotes, you can repair them through fragments, which you obtain when destroying items in your inventory;
3) As per 1.11 update, you can now dye your clothes too;
4) You can now respec your character through rift crystals;
These are the substantial chances which are most important for the offline aspect of the game.
As you can see, aside these somewhat nice addition, all the rest is still blocked by the MP wall, especially the bosses rematch (which now play an even more important role for the prestige levels, as they give way more exp than marked ones which are the best way to get exp offline only).
Also, due to the EAC being added, we are getting many issues on the game too, so I'd say to wait a bit and search more before buing this game, as you are interested only in the offline part.