Eh, I bought my PS3 in its first year. Granted, it the only console I have ever bought, but I've never had a single problem with it. My roommate, however, bought the PS3-slim several years after its release and has had to send it in for repairs twice. So who knows?
I have no real plans for when I buy it. It will probably depend on how many new games continue to be released on PS3...and how bored/impulsive I get one day.
I bought my Xbox 360 in its first year, and I never had any problems with it - including the infamous RROD. It was still going strong when I replaced it with a 360 S.
Still have my original PS3 that i bought on launch day, replaced the hard-drive for a bigger one, but still going strong...
Given the fact I bought neither a PS2 or PS3 and from what I'm seeing ... I don't think I'll wait for PS5.