Quoted By:
Here's the early reveals for the past gens for comparison.
Gen 6
>January 8, 2013 - Pokemon X & Y Announced, Gameplay Shown, Chespin, Fennekin, Froakie, Xerneas & Yveltal (shown but not named)
>February 14 - Sylveon (didn't say the type)
>April 6 - Mega Mewtwo Y (didn't explain anything about it)
>May 14 - Riding on Gogoat, Lumiose City, Fletchling, Pancham, Helioptile, Gogoat
>June 11 E3 Direct - The reveal of the Fairy Type & Pokemon Amie, Vivillon, Noivern
Gen 7
>Feb 26, 2016 - Sun & Moon Announced
>May 10- Starters Revealed
>June 2 - Legendary Info & Explore the Alola Region
>June 14 - Pikipek, Yungoos, Grubbin, Battle Royal
Gen 8
>Feb 27, 2019 - Sword & Shield Announced, Starters Revealed
>June 5 - Wooloo, Dreadnaw, Corviknight, Gossifleur, Eldegoss, Wild Area, Dynamax, Max Raid Battles, Leon, Hop, Magnolia, Sonia, Milo
>June 11 (no official youtube trailer but E3 demo and direct footage) - Nessa, Yamper, Impidimp, PSS, No National Dex announced in an interview
So I'm expecting at least we get some Route 1 mon, but there'll likely be even more stuff thrown in.