Well I guess you could say that nothing is impossible, however the cost and practicability of this doesn't work out you can get a G750, G752 either one for about the same cost with out modifying anything. A more direct answer would be that the GTX 880m would not drop in, many modification would be needed and the current cooling system would also need to be modified. And a VBios would need to be written as well as the system BIOS would have to be modified.
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro