We have been following the tamagotchis since they first became popular in the Japanese market, and a Berkeley faculty member bought a set for experiments as soon as they reached the US market.
Events like the child who committed suicide when her tamagotchi died are quite different from the average person's experience with the tamagotchi. If you want more details about why I think this happened I can give you a fuller explanation, but I find this far less important than the kind of shared experience that most people go through with this virtual pet.
The most important part of this phenomena is why people find these virtual pets attractive. I think that there are two basic reasons behind this. The first is the attraction to new technological items (and is related to fashion and marketing). The second involves some basic human needs (like nurturing and caring for another being) and the prospect of answering these needs in a commodity that requires very little continuing involvement or effort. Tamagotchis offer the buyer an easy and simplistic way of thinking they are answering this human need for nurturing without really having to make an ongoing commitment. Some people buy pets instead of having children, as a less involved way of answering this need to nurture. Though pets require less ongoing care than children (and for a shorter period of time), this is still too long, involved, and messy for some people. Tamagotchis require less real effort and the commitment is for a much shorter period of time.
But, of course, the nurturing experience of a tamagotchi is really just an abstract of the full experience of nurturing a child. But it is a very common late-20th century phenomena to think that we can purchase a commodity to give us the illusion of a full experience while our experience is just an abstract of the real thing. For example, many people eat dinner at McDonalds and call it a "meal".
If people find in tams an easy way to give affection, are they going to get used to give affection to a mini computer, instead of a human being, or will they remember the tams are a video game ? And if they get used to it, who is going to give them some affection (because the tams won't, right?)
At first most people will remember that it is a video game, but over time people are likely to forget that. Part of that problem is in vocabulary: that the more people say that they're "taking care of" their tam, the sooner our language will stop differentiating between "taking care of" a virtual pet and "taking care of" a real one. To return to the McDonalds example, many people say they "had a meal" when they went to McDonalds (but in the past a "meal" referred to a lengthy process of people sitting around a table taking and enjoying good food in a relaxed manner). Many people now say they "watched a movie" when they rented a video (and in the past "watching a movie" meant going on an outing and sharing an experience with many strangers in a large room). Today, many people grow up without ever knowing the joy of a meal as a process or viewing a movie as an experience. I think that there's a real possibility that in the future, as a result of the tams, many people will not know the real experience of taking care of another being. And when that goes away, as you pointed out, things like reciprocated affection are also likely to either disappear or be greatly diminished.
The tams and the programs which will copy it soon are they considered as video games or as more by the users ?
Though on one level users are aware that these are just games, on another level they forget that. And again, over time they are likely to recognize the differences less and less. Back to my comparisons again: though most people confuse McDonalds with a "meal" and watching a video with watching a movie, they would recognize that there is a difference if someone pointed it out to them. But they wouldn't think that that difference is very significant. Over time, people who have virtual pets will probably still recognize that this is not the same as having a real pet (though they might not recognize this unless someone points this out to them); but eventually they are likely to think that the difference really doesn't mean much.
Some people tell me that it is a "fashion" of the moment as the "dolls to adopt" were. Some wonder if the virtual friends are going to play a part in our everyday life some day. What do you think about it ?
Yes, this is very likely. Science fiction writers have written about this. For example, Philip K. Dick wrote a book called "Do Androids dream of Electric Sheep" (which was made into the movie "Blade Runner" but the movie didn't include the parts about the virtual animals).
Background interview for article slated to appear in Sept issue of "Science et Vie"