Success i think to most of the projects is long term development. Many projects at this moment are dying in a sudden after their campaign period. More likely, projects are being drag down by the market behavior. Long term plans I think is rare to most of the projects. Projects nowadays are easily giving up when things do not go with their expectations. Projects which are having huge plans in the future are those who are fighting for survival at this point. Just observe those projects who are running for years already. Popularity is getting bigger which would be good for future developments and progress in general.
For me, if we are talking about new projects, a successful project is simple! Once they deliver the product whether they follow their roadmap or even there was such a delay, they will still deliver the project, a working one, maybe there are flaws but surely improvement is there once it is being tested. That is my take for a successful project.
It won't be a success but rather accomplishment. If their goal would stop at a point wherein they delivered their products to theit consumers, it would be the end. And that simply is not a success. A success is something continuous.