Honestly, I would love something like this to happen! I feel like both of them have a lot to add to the cast and the group dynamics. On the heart-wrenching scale and the funny/cutesy scale!
Maybe this is me watching too much love comedies growing up, but I feel like Taranza would STILL have trouble admitting he "likes" likes Sectonia , even if she were to come back to life in her right mind!
Like, he'd be happy and he'd hug her and there'd be tears and then he'd start to say a bunch of things he couldn't say but when it came to admitting WHY he's so happy she's alright, he would start to stutter and stammer and, "I-I need to fix my hair! I'll be back!"
(The two of them would probably figure it out eventually, although several characters being part of the "kiss already!" cheering squad as they continually dance around each other would be fun to see too.)
And it would be fun to see Haltmann pivot to being just a funny, over-protective dad. It's the way he laughs during his boss fight, but I like to imagine him as something of a hidden goofball. But then, when it comes to Susie, he gets super serious. When Susie casually mentions she has a rivalry with Francisca, the next morning, Susie campaign signs pop up a~ll over Dream Land XD
I can't help but think it would be a LITTLE fun (okay, a lot fun) if like Magolor, they kept some aspects of their corruption. Like Sectonia still gets a little possessive about things: "Ooh, Taranza! I love this place! We should ANNEX it!" "M-my queen, I'm not sure King Dedede would like that." "Oh... ._. Should we go to war with him to make him give it to us?" "Q-Queen Sectonia!" "Kidding, Taranza!"
Or pit Max and Magolor in a comedic business rivalry for who can earn the most money selling trivial trinkets to the residents of Popstar. Little situations like that!
Basically, if I had my way and there was a new Kirby anime series or a (serious) Kirby manga, I would want both of them to survive their games and be healed, so that they could hang around and contribute to future adventures. Sure, it might be a little idealistic, but these would be spinoffs, so really, what's the harm?