Is the question something more like...
Sony have had two very strong devices in terms of units sold, managing n million in m years. If PS3 doesn't sell as strongly, what is the minimum number of units sold in m years that you think Sony can be happy with as maintaining a strong brand?
I can at least the point of such a question as that anyway, even if I wouldn't care to partake. Asking how many units makes PS3 a success, without defining success, and not caring about the other platforms, just confuses me!
Similar but not quite. The "brand" will be strong regardless. The PS3 platform itself is a whole other subject. Also guessing what "Sony" is thinking is impossible hence I limit it to ones personal opinion.
Sony have had two very strong devices in terms of units sold, managing n million in m years. If PS3 doesn't sell as strongly, what is the minimum number of units sold in m years that you would consider a success for the platform?
Thank you for clarifying my question though!