Honestly, even for funded startups scale is generally the last thing one should worry about... it's the single best problem to have. If you're doing it because

Honestly, even for funded startups scale is generally the last thing one should worry about... it's the single best problem to have. If you're doing it because you love it just do it, wikipedia exists on donations. Worst comes to worst you decide you can't afford hosting anymore, and you either limit traffic, or shut it down and paste a link to the code. It's not like you owe anyone anything for having provided them a free service for years.