I LOVE the tools Astute provides. I've used their trial period to work with many of them, but have only purchased a few as they're spendy! (Worth it, but spendy!)
I would guess Affinity/Serif would just need to contact Astute and work out integration, but then let Astute provide the plugins. That way Affinity can stay the same price, and people can choose what plugins they want to buy from Astute.
I reached out to Astute to see if they'd be creating plugins for Affinity and this is their reply:
(Red and bold my emphasis.)
So how about it, Serif?? Are you going to contact Astute? Their plugins really rock, and this would really make huge strides in comparability between Illustrator and Designer.
Here's their contact info:
enquiries@astutegraphics.com
Nicholas van der Walle
Managing Director Astute Graphics Limited
Penn House, 9-10 Broad Street
Hereford HR4 9AP, ENGLAND
tel. +44 (0) 1432 341073