I'm fairly confident he can get 2%, but an optimistic 3% is very realistic. His poll numbers have been consistent and steady, he already has twice the name recognition that he did in 2012, its very hard to see 80% of his support just going away.
it did in 2012.
Can you point me to a poll where he was at 10% or more in 2012?
How about 6%?
Bob Barr hit 5% in the polls and managed 0.4% of the vote, so it's really inconsistent.
OK, but how well known was Barr or Johnson in 2008 or 2012? Johnson has about 25% name recognition in 2016 so far. Google Trends shows he is already searched 41% more than his peak in November 2012, and 20 times more than this point in 2012!
Not to mention not many polls included any third party candidates in the past, this is the first year third party candidates have been included in most polls. So there's just no comparison.