The key to this is user retention, and if reddit users are loyal to reddit (which they seem to be, especially those willing to pull their credit cards) I wouldn't be surprised to see retentions on the order of 6 months or more.
What do you base the 2% on ?
For Reddit, yes you'll get a number of die-hard fans who want to subscribe. But I don't believe that there is a big enough value proposition for the userbase to do that en-masse. They may as well just set up their own reddit since the code is open source (And wouldn't be that hard to recreate if it wasn't).
It might be different if:
A). Reddit wasn't spending crazy money on servers
B). Reddit wasn't owned by a multinational corporation
C). Reddit hadn't pandered to, and cultivated a staunchly
anti advertising userbase.
Also from their latest blog post, it looks like they're just spending the 'reddit gold' money on more hardware! Instead of fixing the underlying issues.
The 'news' angle is a silly one, but they could definitely think up features that people would pay for that are not available right now in the free product.
The real issue with reddit making money from advertising (aside from the ad blocking) is that the CPMs that are quoted here (between 2 and 9$) are not realistic for their number of pageviews. By the time all the unsold inventory is taken out you probably end with $0.05 ECPM or maybe 10 cts per click (and that would be pretty good).
I'm really interested in how much they were paying before for their bandwidth and hosting if going to EC2 actually lowered their costs, they must have had the worst deal on the net for that to be true.
Right now, $30K / month buys you 20 (very) fat servers and 20 Gbps flat rate, managed hosting.
I'd really like to see someone make the case they can get that kind of performance out of EC2 for a similar cost.
And hiring a designer! Because, you know, that'll fix their load issues.
(The point stands, though, that "basic" doesn't mean "light").