I know you're joking but I think nobody will seriously consider a proposal and then implement it if it has very serious limitations as to what types of fonts it can be used with.
Sure, there will always be some limitations (for example, today variable fonts work with TrueType outlines and PostScript outlines but not SVG outlines, and that's accepted as a compromise). But if some functionality requires serious engineering work, it has much bigger chances of succeeding if it can solve a variety of problems rather than just one or two.
Again, I myself would welcome this development (so that variation can somehow become useful on the sub-font, inter-glyph level) but I know it's quite hard, so it'll take a lot of time to even formulate an initial proposal. And it works require someone to actually come up with a specific proposal (that would propose how exactly it should work).
Linotype Univers and Frutiger Next are the late-1990s reworkings which suffer from many problems. Linotype Univers has terrible interpolation compromises (too large contrast in the middle weights), Frutiger Next has those poor forced cursive italic forms. Those projects are like remakes of 1960s films done in the 1990s. Hardly an improvement, so they’re best forgotten.
Univers Next and Frutiger Neue are the 21st-century reworkings. I think overall Frutiger Neue is an actual improvement, while Univers Next seems to improve over Linotype Univers but only in minor ways. Some spirit of the original Univers, especially the great square comoressed cuts, are lost. But overall, they were done in a fashion truer to the original spirit, and under the care of Akira Kobayashi. They’re much more successful reboots within the FTU (Frutiger Typographic Universe).
Terms evolve as does type design. So in today's world, my take is the following.
— cursive is a structural descriptor: when letters have a structure more related to fluid writing than to mechanical composition; it doesn't matter if they're upright or slanted
— slanted is a structural descriptor: when letters are generally slanted i.e. their normally “vertical” strokes are actually inclined; it doesn't matter if they're cursive or not
— mechanically slanted is a structural descriptor that describes the process of derivation: when letters are made purely by automatic geometric distortion (slanting) of their upright counterparts
— optically slanted is a structural descriptor: when letters look like slanted versions of their upright counterparts but have undergone optical correction
— italic is to me primarily a functional descriptor: when letters serve as a subordinate companion to other, typically upright, letters, used typically for light emphasis; however, some people may have a different notion of italic
— true italic is both structural and functional: when letters are structurally both cursive and slanted, and functionally italic — any other definition would be confusing to me; a copperplate script font is not “true italic” because, while it may be cursive and slanted, it is not functionally an italic
— upright cursive is a structural descriptor: when letters are cursive but they are not slanted — oblique is a structural descriptor: when letters are optically slanted but not cursive; in a sense, oblique is the opposite of upright cursive
— upright italic is both structural and functional: when letters are structurally upright cursive and functionally italic
— faux italic is both structural and functional: when letters are mechanically slanted (could even be from an “upright italic”), and they're functionally italic
If “oblique” is purely structural in my categorization, then I’d admit the term oblique italic, where letters are structurally oblique and functionally italic.
The font in question has an “upright italic” (i.e. its italics are an upright cursive). Pluto and Bree on the other hand are upright cursives without being italics.