Quote: "The 3D models themselves will scale, but the textures will not look good scaled up."
Yeah, but if your textures are high enough res by default, it'll look fine (this works well on my project by having 128x128 textures for fairly small objects. Expanding from 1280x -> 1920x screen resolution and it looks great). Unless you have tons of assets (and high res defaults aren't practical) in which case yeah - multiple texture sizes etc. will be needed.
Obviously it depends on what kind of UI and game objects you have though (e.g. repeating texture buttons vs. really complex elements)
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