When wp7 fails microsoft will shell more money and bring you WP8 or bingPhone or whatever. It has failed more times than the version number implies and yet they change the name and try again:

1. Windows CE --> FAIL
2. Windows for Pocket PC --> FAIL
3. Windows for Pocket PC 2002 --> BIGFAIL
4. Windows Mobile 2003 --> SOSO
5. Windows Mobile 2003SE -->it was soso thus we keep the name
6. Windows Mobile 5 --> Let's change the version numbering (and nothing else) BIGFAIL
7. Windows Mobile 6 --> change theme
8. Windows Mobile 6.5 --> ULTRAFAIL
9. Kin --> MONSTERFAIL
10. Windows Phone 7 --> we want to take down others with us ?? I feel they will not fail miserably this time but we'll see