The phonology of Urdu appears to be different enough from that of Hindi because of (however artificial) phonemes not, for instance, present in Hindi as they are of Persian derivation. WP:CFORK simply does not apply because here is not a case of (I quote the "this page in a nutshell" box) "Articles should not be split into multiple articles just so each can advocate a different stance on the subject", since there is no "stance" to be taken, it's just a matter of Urdu phonology being different from Hindi phonology. If you want the differences between Urdu and Hindi phonology to be more prominently highlighted than they are now you can, as I said, do it yourself (you can't expect to force others to add content, surely). As to code-switching, for other languages this seems to be tackled by having a separate article about the common code-switching mixtures (Spanglish and so on) and linking them in the "See also" sections, so feel free to do this if you want, for what I'm concerned.