The obvious 'native' format for Unicode data is UTF-32, which forgoes ASCII-compatibility and gets you regular, consistent sizing. Unfortunately, Unicode itself is an ASCII-encumbered character set (or at least Latin-1-encumbered, and Latin-1 is ASCII-encumbered). Pretty much all the contents of Unicode are there because somebody needed them¹, so I imagine a non-ASCII-encumbered Universal Character Set would still contain all the ASCII characters... somewhere... but they'd likely be shuffled around a bit from the Unicode we know and love.

¹: I believe Unicode encodes some meaningless Kanji/Hanzi glyphs that were created by accidentally confusing two other, genuine glyphs; I'm pretty sure it only does so because it inherited them from legacy pre-Unicode encodings.