The latest Construct updates and browser updates have made possible some interesting new improvements for both video support and images. We wanted to highlight...
It would work only for online games and maybe on limited case only, depending on the game, but load from URL the images should partially solve the issue. Just need to plan ahead what type of game could support such type of organisation.
For example, card games would be easier to handle in this way because the collision box is easier to manage compared to sprites that require irregular collision boxes. Though you could have all collision images pre-defined with proper sprite in the project, then replace all the images just before exporting, using all blank images to save space and then load everything from URL depending on the browser.