I think the fundamental shift that has occurred and carved out this space for Super Angels is that the cost of starting a company has come way down. It no longer takes $1mm to get a startup off the ground (2 guys and a pallet of ramen seems to be standard now). This increased capital efficiency has allowed startups to raise less money to reach the same inflection points that they historically have. As a result, a seed round of $500k can take a company to the point that normally, a $2mm Series A would have required.

Not needing millions of dollars in capital means that startups don't have to knock on the doors of VC firms with large funds. Instead, they can approach a Super Angel to lead a $500k round with $300k with $200k left for 4 to 6 value added investors.

I doubt that even if IPOs rebound, Super Angels will fade away. I think it's more of a tectonic shift and Series A's are de facto turning into earlier, smaller seed rounds.