A few years ago, I bought my wife a Toyota Sienna. It was mostly top of the line, with SatNav, CD Changer, Bluetooth, DVD player and all the bells and whistles one might want. Well, time marched on, and now the SatNav looks old. I don't use CDs in the car, I use Pandora, or MP3s that I have. The Bluetooth doesn't do A2DP, so I can't play music from my cell phone while in the car unless I plug in. The DVD player only plays DVDs, and not Blueray. It isn't even that old, but it seems my cell phone has passed it by.
Looking back to about that same time for avionics, and things have updated there as well. The GNS 430 and 530 were the top of the line radios back then. Today, we kind of admire the aircraft with those radios, but would rather have the G1000 or something newer, given a choice. How about today, well Garmin hasn't been standing still, and are ready to offer the latest better things.
What should someone do who wants the best latest avionics? I believe we are on the edge of the future. What if the (Attitude Heading Reference System) AHRS and Engine Monitor were mounted in the aircraft, but the display you could update? That would allow some lower cost better newer looking panels.
What if we could use our tablets as the display, and update the software and data over the air (OTA)? Well today people are doing just that. Sporty's sells AHRS's that you can get today that will display the results on your tablet. Today they are only "backup", because they aren't bolted into the aircraft. I'd wager, people with these systems are using them as the primary navigation display, and relying on the less functional panel equipment as the backup.
Say you did a proper bit of engineering to mount the gyros, and added some pitot/static data. Send the data over USB or WiFi to a tablet that would also be mounted in the panel. What is the difference than a panel mount system? It will work for experimentals, and maybe part 91 operations. TSO equipment is required for Part 135, so it won't work on aircraft for hire.
It can be done, or at least something to think about. How far would someone have to go to get one of the tablet systems TSOd. I am sure there are documents that the FAA and others produce that would tell me. That will be my research of the next couple weeks.