On widebodies you'll have to dump fuel before returning.
With no contact with ATC, you'll have to decide where to dump, and after a relatively long time in a hold over the sea (possibly), suddenly come back and fly the approach, hoping the ATC makes a good job in separating other traffics...
Interesting.
Old academic question.
Thanks God virtually impossible these days.
If good common sense clearly says completing a long haul flight with no radio is crazy, perhaps more tricky is the scenario in a short haul 737 flight, maybe with an anal retentive controller checking you in the box.
To continue or to come back?
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I think taking your time is the key for the best solution in this scenario.
Probably I would return if heading outbound, and continue my flight if heading home...
Follow the sid, maintain the last assigned altitude, maintain minimum clean, and when you are far away enough from the mess of the terminal area, slowly make your way to a quiet place where to dump, in the most dirty config allowed for that.
When you are close to MLW, make your way at a slow speed to a long final: that will allow ATC to easily make separations, and that's it.
If you want to continue, do so.
When reaching overhead the field at cruising altitude (!), start descending in the hold and then shoot your approach.
I would do so at a stable 150 knots, for the above reason.