I'm not sure the pause in unicorn IPOs is directly related to a slowdown in seed funding -- perhaps indirectly by minting fewer angel investors.

A lot of the popular press -- even the popular tech press -- conflates startup funding. But late stage investing, which is mostly where unicorns play, is a totally different game from seed investing.

Also, there are two stories here... one is about the shift in average check size and fewer deals. This is really just investment grade inflation, where larger deals are being called 'seed.' Not sure why but it's how it works. So much of the former seed rounds are probably underreported angel / micro fund rounds now.

[Source: my startup's funding isn't publicly disclosed for that precise reason.]