Sure, why not? In fact we already have a few.
There's Hatoful Boyfriend, a dating sim, Long Live the queen, which isn't easy to classify (some sort of raising simulator), and To the moon which is purely a narrative based experience.
And about that...
IAmSinistar: If GOG exercises good quality control and the VNs have enough
gameplay, then I don't see any reason why they couldn't be added to the catalogue. More diversity is typically a good thing (which is why I'd also like to see some of the better kids games, like the Humongous titles, here).
That is the fallacy of Visual Novels imposed by western expectations. Since they are classified as videogames, you expect them to have some sort of gameplay. But the fact is they don't. The term visual novel should be taken literally. They are basically a choose your own adventure book which include images, animations and sound effects as a means to enhance their narrative experience.
The whole "aping some other style" argument, is in my opinion, pointless. It's pretty obvious that the reason most western visual novels are anime-sque is simply due to the creators being first exposed to the genre through japanese works, and thus most western Visual Novels are love letters to those same works.
Which I find ironic because in ye olde days of 8 bit computer gaming, text adventures, the precursors of visual novels were sold and distributed in western markets (ok, even then they were a niche genre, without much success, but that's not the point here). Remember Infocom and their Hithchiker's Guide text adventure? (I actually don't) And then there's
this little gem, which I'd argue is a legitimate visual novel, that I never played myself but which a lot of my friends remember fondly.
If they slowly regain recognition as legitimate narrative devices, we should be able to see new works which stand on their own merits and are not simply appealing to a very specific niche audience.