Unless a senior executive from BSkyB happens to be posting on AB, you probably won't get a definitive answer here.
However, I doubt that the financial aspects of putting Sky 1 on the Freeview platform would make much sense.
Sky 1 would get more viewers on Freview; it would therefore be able to charge higher fees to its advertisers. However, they'd probably lose out on potential customers for their satellite channels, because people would be more satisfied with Freeview and less likely to subscribe to satellite services. Additionally, Sky 1 would have to pay the access fees to broadcast on Freeview. I just can't see the sums adding up in the case for putting Sky 1 on Freeview.
The situation with regard to putting Sky 1 on Virgin Media is more complex but, given the poor relations between the two companies, I doubt that Sky 1 will ever return to any form of terrestrial TV.
Chris