There is no reason that you could not also take up Tai Chi, a lot of the deeper aspects that can be applied to Wing Chun are easier to find in Tai Chi. You can once you know them look for them in the Wing Chun. I also know a guy who has incorporated a lot of the theories of Pak Mei to Wing Chun. This seems to have improved his art a lot as he theorizes a lot of the aspects like sink, float, swallow and spit are neglected in Wing Chun but would have originally had a greater emphases. Skills like whole body connection are also more apparent in Pak Mei and Tai Chi but can be applied to Wing Chun and open the gateway to the more spiritual aspects of martial arts. A working knowledge of other arts more famous for the spiritual qualities of martial arts applied back to the Wing Chun will make it a lot easier to find.
I think Tai Chi being the easiest to find. Xing Yi or Yi Quan would probably be the most productive though if you could find a teacher.
I have studied a fair bit of Wing Chun in the past and done some Xing Yi and Yi Quan (loved the Xing Yi) but know do Tai Chi and Pak Mei as I have found good teachers.