Is it possible to view 'Expired' entrys on the front end?
I don't think you can enable the default Entry Routing for expired entries. So you need to add a custom route.

To keep your current URLs, try to rebuild the default Entry Route with a custom one:

news/{slug}  →  news/_entry

Expired entries shouldn't return 404 now any more and load your entry template. You now have to get the Entry Model manually though:

{% set entry = craft.entries.section('news').slug(slug).status('live, expired').first() %}