LIVEWIRE: afterpay-what-s-a-billion-dollar-revenue-line-worth, page-6

This excerpt from Bear's link sums it all up:

If it plays out like it did in Australia, customer growth could accelerate to 10k a day and beyond. This equates to ~3.5m new customers in the US over the next 12 months, a doubling of APT total customer base. To put it simply, the US is scaling roughly 5x faster than Australia, in a market >10x the size.

If we assume APT deliver $25B GMV at ~ 4% merchant fee, then APT will generate $1b of revenue.

APT has also guided to a 2% net transaction margin (NTM) on this revenue, implying $500m of NTM. Assuming $150m of corporate overheads would imply 350m profit before tax or NPAT of ~$250m. Given the growth profile, customer unit economics and global growth opportunity that APT will still have at this point, we would expect APT to trade on a PE of 30-40x. This would imply a market capitalisation of $7.5-$10B or $30-40 a share.

However, the valuation of SP of just $40 at that time is still conservative. Reason being, once established in US and if in UK, rest would be much easier to expand with their established brand name and experience. So, the valuation of SP at $40 doesn't take the future growth outlook and sentiment into account I reckon.