the ability to buy ACTUAL houses like Michael's and Franklin's mansions.
GTA: Online is in the same world as the singleplayer with certain characters like Trevor and Lester, so they still exist; therefore, that wouldn't be possible, unless Franklin and/or Michael went into debt (which for major heisters, seems unlikely).
dude.. reading comprehension.. did you even read his post? he said houses like michaels and franklins mansions.. not their same exact house that they live in.. besides that, franklins mansion was given to him by lester. lester could "give" us the same mansion, or another one.
I personally, would love to live in a trailer in blaine county.. but I wouldn't have a 10 car garage.. I'll settle for a mansion.