There are other threads across the forum in regrard to the Adsense Refferals program. Search the forum and read.
It never worked well for me I doubt they will bring it back. Nowadays their word of mouth advertising is huge, so why should they pay people to refer someone to their program? Chances are that person already knew of Adsense and is just agreeing to click someone's affiliate link.
This isn't just about google adsense referrals... it is about all referrals within the adsense program that they are retiring. It did attract some good paying affiliate products... but you weren't allowed to promote them the same way you could promote other products by building landing pages and mini-sites around that niche. Also, google seemed to want people to promote whole categories yet they never enforced monitoring of categories properly... so people had loads of products listed in various different categories and made it unattractive to webmasters. A few people made $1000s, the majority made hardly anything compared to contextual ads or other similar affiliate products on other networks.