The new mac pro does not support cuda, wich is becoming the standard for 3d production and editing, it is not a good investment.
External gpu solutions for a mbp are a waste of money.
There are better solutions than the mbp for this segment but the most workable ones come with a 17" format wich apple no longer provides, because it was no longer their market, and they never actually invested much on it ( usually same specs of he 15") they kept te same thin design of the 15" wich of course limited these machines in what components they could use. A current 17" workstation It is Of course less portable and ticker but they still outclass the mbp in performance and expandibility by a huge margin.
The ticker design is needed for cooling, there are no other ways around that. Powerful gpus needs a lot of energy and heat dissipation wich cannot be provided on a thin form factor.
Check an asus rog j750z for example, its thick as 3 rmbp in the back, but it comes wih 2 individual cooling system ( one for cpu one for gpu) wich allow the machine to operate silently (under30-35 db i guess) under stress. It also has a gtx 880m but the external temperatures dont go past 35c. Internals dont go past 70c. Keyboard feels barely warm. Because of the size the machine has room for 32 gb of ram, dual ssd raid setup, and another 2 slots for hdd/optical.
With apple design instead you have a great,very portable all-around solution, the performance provided is very good for the size given the compromises needed for it.
The only way for top performance for apple is a new 17" model but with a custom design, but this will never happen. Nobody would buy a 4 cm thick mbp, apple always advertised the thinner design as an improvement on every product they made, and it is what actually benefit the majority of their users.