I think it's an indication of website get some kind of penalty or is going to lose its page rank in the coming updates
It all depends on Google's mind to give PR. No matter how many Back links it has. The site's importance in the Eye of Google is PR.
No! even i visited the site today. I can see PR 3 and no backlinks. Its quite strange dear. I really have no words to say.
That seems no possible. If no back links, what does google use to identify the importance of the site?