Possibly so, although it's difficult to think of a reason why they would demand people screw around with physical SD cards when it's obviously possible to do this stuff over WiFi or HSDB, as the GI-275 has proven. Ideally, I'd like to see all of the Garmin Avionics share and share-alike regarding databases and sensor data, which is perhaps unlikely but seems technically feasible. Failing that, any G3X Touch successor should at least have the same connectivity capability as the GI-275. If I have to separately update the display, at least make it more convenient!
When the G3X began life, I believe that it was only for experimental aircraft. The original G3X came out in 2009. The G3X Touch, still experimental-only, came out in 2014. The approvals to install it in certified planes came in 2019. The G3X family talks to its own LRUs with CAN bus and has some RS-232 connectivity, but the main data pipe between a G3X and a certified navigator (GNS or GTN) is ARINC 429, through the GAD 29 LRU, which talks to the G3X stuff by CAN bus and to the certified stuff by ARINC.
It is possible that they just wanted to keep things simple for builders by omitting an HSDB connection from the G3X. The CAN bus has the advantage of being really easy for an amateur builder to wire up: just a daisy-chain of 2 wires through the plane. For example, my G5 backup display only has 4 wires: CAN high, CAN low, power, and ground. The backup ADAHRS device has the same 4 wires plus a jumper between two pins to identify it as #2. Most devices in the chain don't have much more than that, except for the audio panel. Most of the wires in my plane are for audio. Including the wires I had to add after closing the thing up. The only HSDB connection I have is from the GTN to the transponder. A simple enough G3X Touch panel might not need any ARINC or HSDB wiring at all.
It is also possible that they kept HSDB out of the G3X specifically to make a firewall between the certified navigators and experimental LRUs. If that's accurate, then it has fallen apart with time. My GTN talks to my G3X by ARINC 429 (3 channels: GPS and VHF nav to the G3X and air data back to the GTN, all via the GAD 29 converter box and CAN bus from there) and RS-232 (2 channels: Connext and MapMX). But this could have been a factor in the decision to omit HSDB from the G3X.
It wouldn't take much to rectify that in a successor. They have tended to keep backwards compatibility with G3X LRUs, and I personally hope they continue that so I can replace just the displays in my system (same size, mounting screw pattern, and connector pinouts). But they might find unused pins on existing connectors and/or add an HSDB connector to the GDU displays.
I think that adding HSDB would also improve interoperability with the GI 275, helping them sell more of those to the experimental market. And it could save new panels from needing the GAD 29, any ARINC 429 wiring, and most RS-232 wiring (I would probably still wire the RS-232 backup channels from the engine monitor and ADAHRS to the PFD). You'd have a star topology instead of a ring (PFD directly to MFD, GTN, GI 275, and GTX) which carries different failure modes to be aware of but isn't a bad thing. I think that's how the TXi systems get wired up, anyhow.
All I know about any G3X Touch successor is rampant speculation. To my knowledge, Garmin hasn't actually said anything about it. I am just hopeful that they hit another home run with it as they did with the G3X Touch.
. But, as I am planning the panel for a 210 that should be forthcoming, I am budgeting in the yaw damper servo...no doubt. I have a pair of GI275's along with a GTN650/GFC500 in the 182. I have flown behind G5's and there is a huge difference in functionality with the 275. That is a great upside but....there is a lot of information packed into a small space and I am still getting comfortable with it after about 70hrs with the package. I am caught in the debate between going with three GI275 units (one for EIS) or a G3X 10" and 7". I've got the budget for the latter, assuming the 182 sells for what I think it will go for, but it certainly will be quicker to install the 275's in the existing overlay. Definitely high bottom problems we are considering in this thread. 
