I wish that was the case, but going off of 2008 results I don't see that happening.
Paul got 1.1 million votes in 2008 primary
LP + CP in the general got 723k votes (~66% of Paul primary voters)
Now, LP membership in in 2008 was ~250k, I'm sure most didn't switch over to vote for Paul in closed primaries. I can't find CP membership but I'm going to assume 100k nationwide (please correct me if you have the actual numbers) I'll say at most 20% of them switched over then switched back, which by reading LP press releases this sounds about right. I will also assume every member of this 80% voted in the general (I don't know what percent of the LP actually votes, once again please tell me if you know)
So 723k - 280k = 433k. Now, this number will probably be lowered once again since we can't assume all 433k voted for Ron Paul in the primary, or even voted in the primary at all. In conclusion, I can only say based off of the 2008 results that about 1/3 Paul primary supports will vote third party. I would suspect the number to be a bit higher than 1/3 in 2012, but definitely not 90%. Also, it looks like the LP and CP should more than double their numbers from 2008 in 2012.