I would agree with your estimation of a little over 40k existing EB2-IC applicants ahead of you at when FY2012 started. Let's call it 40k for sake of simplicity.
If 30k visas were available to EB2-IC this year, that would nominally reduce the number needed to 10k.
That number is probably within the buffer range that DOS might consider to have an inventory beyond what can be approved in FY2012 itself.
Adding Porting would increase this, so it might rise to 13-16k, which might be pushing it.
I think when people talk about May 2008, that is based on DOS moving the Cut Off dates based on 35k, including any buffer and assuming 3.5k Porting / cases from FY2011. People in the buffer zone would be able to file I-485, but not be approved.
Based on that scenario, it would require another 10k in FY2013 (excluding Porting) to move the Cut Off dates to the middle of October, so that might be possible in the first few months of FY2013.
See this
post, which you probably have already looked at.
At the moment, I think 30k actual visas is too optimistic for FY2012; movement of the Cut Off dates to account for 35k is not impossible, but who knows with DOS?
I wouldn't necessarily agree that PD in 2008 are "light. See this
thread. You will have seen the beginnings of a discussion about how numbers of remaining cases might be affected by the recession about that time.
In summary, I'm not wildly optimistic about you becoming Current in FY2012 itself.