The hardware companies will like that I think. More OSes will mean that people need to upgrade more often, or stay with the old OS. This would most likely result in more sales for the companies.
In the past, Microsoft released an OS more or less every two years, 95, 98, 2000, and 2001 (XP). So, I think it's just a matter of time till they consider it common again to upgrade every two years.