There hasn't been a single bad issue in Spencer's run from #802-829 (which is 28 issues around the same number of Roger Stern wrote). So its still high summer for him.
It depends on the execution. A plot twist that people guess can still wow people over if it's done in a very dramatic and consequential way.so I’ll keep my hopes up. But I do wonder whether the payoff will equal the buildup.
Mystery villains in comics, and mystery stories overall, have gotten harder to do since the rise of the internet and the online community. The last big successful comics mystery villain was HUSH, and that entire story ran a bunch of misdirections and red herring even when it was quite obvious who Hush would ultimately be. The terrible thing is to cheat the audience just for a shock (which is what the horrible HUSH cartoon movie did). Likewise the Hobgoblin mystery which cheated several years worth of readers with that awful copout of Ned Leeds being the Hobgoblin and which ultimately didn't get fixed even with Stern showing it was Kingsley all along in the '90s.
The key is how our attitude to Kindred will change from Pre-Reveal to Post-Reveal. Hush for instance was cooler as Mummy-Face guy than he was as Tom "I'm Totally Evil Bruce" Elliott.The other real problem with Kindred is that so far it's a mystery that is played with the audience rather than Peter. Spider-Man doesn't encounter Kindred, doesn't confront him or has any curiosity/paranoia about who he could be (which is what the Hobgoblin mystery ran on).
So it feels like Spencer is playing this game with the audience rather than Peter.