Now that the announcements work in TSW6. And DTG was thinking about bringing it to some of the " older" routes. I think The Goblin/ Suffragette line would be a good candidate to implement the announcements. It will benefit the immersion on this route.
CCN, WCML, ECML, Edinburgh to Glasgow, Cathcart, SEHS, BCC and both Overground routes I would like to see the most.