Yes, I considered this option. A sure way to get rid of this and future changes in Tcl types, is get rid of Tcl_Obj at all and always return strings (if it is not a number or list). The drawback of this method is that occurs unnecessary conversion between Tcl and Python types and that information about types is lost. Also it is possible to hamper support for new Tcl types (dict, StateSpec, etc) in  future.

Another way is much more difficult. We need to allow all Tkinter functions to accept Tcl_Obj. Unfortunately this doesn't solve the problem fully because other code might expect a string instead of Tcl_Obj. We don't have enough test coverage to verify that the changes are sufficient. In any case, there are third-party code, which will also have to change to support the new Tcl versions.