(b) Who could dethrone him this year? Maybe a better question is, which race will first? [For sure it won't be Zerg—he dominated Dark and Rogue, so I give basically zero chance of any lesser Zs beating him, basically implying all other Zs.]
(c) It'll be Terran(s): INoVation, Maru, and TY could still take out Serral, any doing so being far from upsetting—at HSC, a (relatively) rusty TaeJa barely missed taking him out 3-1. [God it'll be lovely if the TaeJa-of-Old emerges!]
(d) INno barely missed doing so in the same tournament. INno is in great form again, possibly like his form of yore. [For you young bux out there who missed the Age of the Machine, there was a time, a very long one, where INno did to KRs what Serral does to foreigners.] Without doubt INno could beat Serral this year.
(e) If not by INno then by Maru. Maru is the most naturally talented SC2 player ever. Maru at his best could handily take out Serral—you'd be a fool to be surprised if Maru ever 4-1 or 4-2'd him in a Finals.
(f) TY still has his moments. On-point TY could beat Serral, but it'd be extremely close.
(g) Zest, Classic, and Stats could still do it, but I find it unlikely. If I had to pick which of them would, it'd be Stats.
(h) Serral could, and likely will, be around a long time. He's patient, low-neuroticism, and maybe most importantly, can consistently reverse-sweep—off the top of my head, I can't think of another player that consistently comes back and wins when big money's at stake.
(i) I know we all have occasionally had our nuts speed-bagged by what-if? "Dream Finals"—crowdfunding could create those Dream Finals and answer many what-if?s. If we don't get the tournament finals we want, crowdfund them. It'd help keep the SC2 scene alive since as long as players have the opportunity to earn big money, they'll stay. At any rate, we need to look into ways to keep such a beautiful game from dying a slow death when its current skill-level is undoubtedly the highest in history. We really need to explore crowdfunding Dream Finals and the like.
(j) Serral is a lovable guy and I wish him the best in SC2—his play is truly inspired. But far more importantly, based off the 2018 WCS Finals promo video about him, he seems like a damn good man.