Well, it's not necessarily Bruce Lee's shoes that Philip Ng has to fill. Rather it is the shoes of one character (Cheng Chao-An), and I have no doubt Ng will do an even greater job at fleshing out the character than Bruce did. "Once Upon A Time In Shanghai" had much of the same gritty and dark feel that Big Boss had, and almost all of the main cast dies in the end. OUATIS's director, Wong Ching-po, would also be suited very well to direct a BB remake.
This is a personal peeve of mine, but I find it slightly annoying how, 46 years later, there doesn't seem to be many movies with traits similar to that of Big Boss. Considering how infectiously influential all of the Bruce's other films were, one would figure the same would be true of BB, but for some reason it's just not.