I hope you keep the original Swift's concept of using off the shelf bike parts where possible (100/135 hubs for example). Hopefully a normal 1-1/8" external headset, the Swift's 1-1/4" is hard to find now.
More tire clearance would always be nice.
I know I'm in the minority, but I really prefer rim brakes on a folding bike. It's just less to go wrong when folding, simpler, lighter, etc. But I expect it's hard for companies not named "Rivendell" to sell rim brakes in 2022.
And I said in another thread, I would love to see a larger size. I have to use a 130mm stem and a bar with some forward sweep to get comfortable on my Swift. But, I'm 6'3".
I like steel bikes, but the aluminum Swift rides decently and is presumably lighter and cheaper.
And +1 to Schwinnsta's comment about the oddly high bottom bracket of the current Swift. It should come down some.