You're acting like this probation deal is forever. They'll be fine by 2013. Also, the fact that the PAC-10 is a weaker conference should lead to winning big. It's much easier to make BCS games with a program like USC in the PAC-10.
Oh really?
This a mathematical perspective from an SEC fan to a Trojan:
I assume you have 85 players on Scholarship now.
I count 20 Seniors on your roster
In January 2011 you lose those 20 guys which takes you down to 65.
In February you can sign 15 up to 75 total. In other words you can only sign 10 in this class if you have less than 85 now you can sign a few more but regardless you will be limited to 75 total for the Fall of 2011.
Lets assume all of those guys make it in you will play the 2011 season with 75 players.
I count 33 Juniors on your roster
In January 2012 you lose those 33 guys which takes you down to 75 - 33 = 42.
You will have spring practice with 42 players on scholarship.
In February you can sign 15 up to 75 total. In other words you can only sign 15 in the 2012 class. Lets assume all of those guys make it in you will play the 2012 season with 57 players.
I count 21 Sophomores on your roster
In January 2013 you lose those 21 guys which takes you down to 57 - 21 = 36.
You will have spring practice with 36 players on scholarship.
In February you can sign 15 up to 75 total. In other words you can only sign 15 in the 2012 class. Lets assume all of those guys make it in you will play the 2013 season with 51 players.
So for Spring Practice you will have
2011 -65
2012 - 42
2013 - 36
And for Fall for actual games you will have on scholarship
2011 - 75
2012 - 57
2013 - 51
Those are the numbers - assuming you do not lose anyone to injury, grades etc etc
They may be a little different with how you use your red-shirts on the Juniors and Sophomores but after attrition I would be willing to bet the numbers will be close.
The good news is in 2014 you can sign 25 - that gets you back to 76 and then in 2015 with another 25 you will be close to 85 - my guess is you will not be back to the full 85 allotment till 2016 with the majority of your roster Freshmen and Sophomores. This will be very good for your 2017 and 2018 years but that is a long way off.