$/sub, sub growth, 'cost of acquisition' of each sub, (and assumptions about margins) is what 95% of the valuation is based on.
Now that they are 'going IPO' they're not going to be judged so much on 'lofty ambitions' and 'intangible market opportunities' - they are going to be judged mostly on 'how much free cash flow' they can generate over time.
So, $/sub (minus the cost to acquire each sub) and some assumptions about operating margins gives you the how much free cash flow per customer they can expect. This is widely different on different platforms.
Sub growth tells you how many customers investors can expect over time.
Hence profits.
Obviously it's very crude, and there's a lot more to it - but that is the most essential, basic economic equation that investors will look at to determine a valuation.
Snaps $/sub right now is negative at the 'net' level - i.e. after R&D, etc. - but the key metric people will be interested in is the 'gross' revenue (and profits) per subscriber. The idea being - one day, 'R&D' costs will stop growing so much, and customer base will still grow quite a lot. R&D and Operational costs are spread over an ever increasing user base, which will put the per-subscriber net margins into the positive.
