I predict the game will end up with at least 5 million before year's end. When they do the inevitable GOTY edition that includes the DLC by this point next year I think it will sell 7mil Lifetime. It will be the most successful game Insomniac has ever had and I am happy for them. They are continuously rated one of the top 10 places to work in US, have a sharp pedigree in the industry, they deserve it.
This will also open up quite the door for them with working with Disney. Many might not know this but Insomniac has 2 studios. One in California, the newer one in North Carolina. They really didn't seem to have enough work to support having two studios. Several of their last endevours were complete busts or just not largely successful, like FUSE, Song of the Deep, or to a much less negative extent Sunset Overdrive. but this changes that. Spider-Man 2 is all but assured to happen with them now. I love that they are seemingly able to do this without being controlled by any one publisher. Publishers have too much say in what goes into a game, it is indicative of an industry that has far too many "me too" games. Like every game being a MOBA or Battle Royal these days. Them being allowed to work with what they like is very beneficial.