The GTN line was released, what 11 years ago? I don't think the screens are all going to explode next year.I find myself somewhere in the middle on this. The GTN 750 touchscreen interface is decent and manageable in turbulence if you use the side of the radio to anchor your hand. The GTN 650 is less intuitive and annoying to me because of the lack of real estate on the screen and having to navigate through a few screens to get the same thing done. The GPS 175, GNC 355, and GNX 375 are in the same annoying category for me, too many screen changes and taps to get something simple done.
That's just the interface complaints. Wait for a few years and let's see how well these touch screens age and if they'll be serviceable when they don't work anymore. I've had several touch screens in vehicles and consumer electronics fail and I'm not looking forward to the idea of an expensive piece of avionics failing.
The only thing that was really lacking in the GNS 430 was the ability to add airways. Garmin would have been far smarter to build a face lifted 430 with a higher resolution screen and an improved processor that was slide in compatible (or almost slide in compatible) with the old 430/530 navigators.