Adding to that, I still think that they need to resurrect "Mr Toad Wild Ride" and stick it in the UK pavilion as it would fit in so well.
Italy needs the most help, but I can't think of anything.
In order to make World Showcase a full day "park", the UK pavilion would have to go big and add a "Through the Looking Glass" dark ride comparable to Curse of DarKastle at Busch Gardens Williamsburg. Doesn't matter how successful the film, a big attraction is needed there. Make the courtyard and gazebo stage part of the queue. If they need more room for it, tear down part of the 60,000 sq ft Millennium Village (they can't be using ALL of that for F&W Festival).
With addition to Ratatouille 3D in France, a Werner Stengel (while he's still alive)-engineered roller coaster in Germany, I feel like the only thing missing where there's space available would be an addition to Canada, like a log ride. Even though wood is only around 4% of their exports, it is their fastest growing industry over the past 20 years.
So, other than shopping and dining, let's recap:
2019: Canada: O'Canada! +
new log ride ($15M) (smaller than Splash)
2022: UK:
new dark ride ($100M)
2020: France:
new Ratatouille ride ($100M) (replaces/expands Impressions de France)
Morocco: music show
Tokyo: Taiko drum show
American Adventure: American Gardens Theater + American Adventure
Italy: Flags show
2021: Germany:
new roller coaster ($21M)
The Outpost: Drums + Drink station
China: Reflections of China + Acrobats
Norway: Frozen, Frozen, and more Frozen
Mexico: Three Caballeros
Odyssey: special events