You know, I'm struggling to think of anyone aside from Tom Baker who actually suffered from typecasting.
Hartnell was old and practically unable to act anyway by the time he stepped down, Troughton had had a decent career and had more of a decent career afterwards, Pertwee did Worzel Gummidge in addition to his long and distinguished comedy career (incidentally, he took the role for the same reason Eccles did but in reverse: Eccles was a serious actor who wanted to show he could be more light-hearted, Pertwee was a comedy actor who wanted to show he could be serious), Peter Davison had been Tristan Farnon and has done many things since then (A Very Peculiar Practice, Campion, At Home with the Braithwaites, The Last Detective, Distant Shores), Colin Baker had been Paul Merroney and has had a decent career on the stage since being sacked, Sylvester McCoy had a very good stage career beginning just before he got into Doctor Who which he continued once he left and Paul McGann barely managed a cup of tea as the Doctor. Literally, IIRC.