Well, I think developing a 'transpersonal identity' is just something to be aware of as a possibility; for some folks it could be a totally valid transitional mode of being between the ordinary default personal identity and a more open-ended, less-identified in general way of being.
I think the thing to watch out for is if one is entering practice with subconscious blocks around experiencing the instinctual and emotional and relational aspects of life. The transpersonal identity can be a dissociative escape from earthly felt experiencing and relational complexities.
So if you feel committed to encountering and living your life fully, in a human and relational way, then you have little to fear about getting 'stuck' in a transpersonal identity

In the meantime understand that at some point, the process of awakening will overtake your ability to make sense of it, and "you" will be subsumed in that process. It makes a difference whether you set out on a path of investigating and becoming liberated from the identification tendency, on the one hand, or on the other set out on a path of shifting identity from the personal to the transpersonal level. It seems pretty clear that many direct path and nondual teachings are attempting the latter. The great value of the buddhist traditions with which I'm familiar, from Theravada to Vajrayana (both of which include direct path elements), is the emphasis on outgrowing the identification habit altogether.