I think the recent Corki hype has everything to do with Triforce and almost nothing to do with where Corki is as a champion himself.
A couple of patches ago, Corki had his mana costs readjusted to make him less of a resource hog in lane, but his kit has basically remained unchanged since season 2. As a champion, he's in a good spot.
Triforce, however, is currently a problem. I really liked the Phage change at first, but even before everything blew up I felt the cost reduction was too generous. Triforce was already cost-effective after the buff to its combination cost (300 gold -> 3 gold), and this change to Phage cut its cost by another 215 gold (Phage went from 1465 -> 1250 gold). The cost reduction and reliability of the new Phage / Triforce made it a must-buy on many champions and brought a resurgence of some favourite season 2 picks, Corki being the foremost among them.
Without the recent Triforce change, Corki would still be in his own little niche, not too popular, but not fading into obscurity either. His potential as an AP mid has also been explored by some people (myself included). Now with this latest patch, he's seen a resurgence in solo queue and competitive play not because of a metagame shift or a change to his kit, but rather a much too generous buff to a classic item.
For solutions to this situation, I feel like the changes that are being implemented on the PBE is a step in the right direction. The stats on Phage and Triforce remain untouched, but the item costs are being readjusted, which is super nice. Right now it is sitting at 1350 for a Phage, and on paper I think it looks fine. I wouldn't mind buying Phage at 1375 or even 1400 gold for the movement speed and kiting potential it gives though, so that's always an option if you guys feel like the current changes are not enough. But please re-consider nerfing Corki, as he has been fairly balanced ever since his mana cost changes.