Last I checked, u/RiotKingCobra said it wasn’t a possibility, though I don’t remember if it was on the discord or the subreddit. Also worth mentioning is that AFAIK Cobra doesn’t work on the balancing team, and as many suggestions as he got on the “poll” post a few months back about ASol’s identity nothing has really come to fruition from it yet since it’s something he’s been doing in his limited free time.
Swapping E and R would solve many issues, and until a Rioter that works full-time in the balancing team (no offense to Cobra here) confirms that it won’t be a possibility I’ll keep my hopes up that it can happen one day.
I would not say that it is off the table entirely - anything is possible - but it is pretty unlikely given the amount of work it'd take, not including time spent validating if it's even a good idea in the first place.
And to clarify, I work full time on the balance team! I'm just not a designer. I'm a quality engineer though I do collaborate super closely with designers every day. While I do not directly design and implement changes on a patch-to-patch basis, I'm usually a participant in the conversations and meetings where we discuss them!