No. Robots cannot replace a real human companionship. It may become a common alternative in the future but there are several reasons why robots can't replace real human companionship.
1. Interaction. One of the key features that makes human interaction unique is gesturing and body language (dilation of pupils, facial expressions, vocal modulation etc.) The complexities are superfluous. These features are what make human interaction interesting. Artificial intelligence may be able to replicate human construction of sentences and cognitive abilities, but it would take many more decades of research and experiments before every other aspect of human interaction would be replicated in a robot. For now, the best conversations you can have is one with and actual person, physically.
2. Warmth, human scent, emotional sensitivity and skin texture. Scientist are yet to produce human-like robots with normal body temperature, robots with emotional feelings, an exact skin texture of a human, with a human scent. These are variables that we subconsciously and sometimes consciously take note of and respond to. For instance, when the human body secretes pheromones, this scent causes an attraction between members of the opposite sex. How can this be achieved in robots? Maybe in a half-human half-robot droid, which we may only begin to consider it's possibility in the next millennium. For now, human-like robots do not possess these features in entirety. An absence of these creates a void that makes long term companionship with robot difficult to achieve.
3. Results of current human-robot companionship. Few months ago, I was reading an experience of a man that bought a human-like robot to satisfy is sexual needs. At first it was great, as the robot never refused his sexual fantasies, but he admitted that it still wasn't as great as being with a real human. Experiences from other persons agrees with aforementioned. Hence, with the current situation, it is clear that human-robot companionship cannot replace human to human companionship.
Edit: 4. Transition of bond. Looking at it from a different perspective. For example, a robot version of someone you used to know is then created. It would be difficult to transfer the bond you once shared with that person to his/her robot version. This is as a result of some mental blocks; a (sub)concious comparison between the person you knew and the new version in front of you; and the feeling that you've lost the original version, there comes grief. No matter the effort employed in creating this robot version, one may keep regarding it an inferior.
I don't think so, robot are programmed machine and machines cannot things from intelligence outside what it is programmed to do . And this is what makes human special as a creation. If machine is ever going to replace anything then it should be in replacing work and accomplishing certain tasks which would have been a work load to human, but for a friend, no ,no ,no. You do get bored interacting with machine that understand less of ones language.
I sincerely hope not. That would be the end of the world as we know it... However, a human being is so incredibly complex that I do not see that happening soon.