In my opinion TELLO 2 should be TELLO PRO (something between TELLO and SPARK)
1) Intel® Movidius™ Myriad™ X VPU + Enhanced Vision Positioning (to add also front sensors) - providing active tracking / obstacle avoidance and "Follow me" mode
2) SD card slot and/or Internal memory 8GB - rapidly clear the bandwith and latency
3) 5Ghz Wifi 802.11ac - avoid the 2,4Ghz noise and raising the distance
3) Brushless motors - prolonging durability
4) Integrated AIRMAP app - to help fulfilling UAV rules / to log flights automaticaly
I would have no problem with double price of TELLO for this, but honestly - this is not so far from SPARK.
Expected DJI (common for Apple-like and other "closed enviroment" builders) product strategy:
New -> Mavic Pro 2
Mavic Pro -> Mavic Air 2
Mavic Air -> Spark 2
Spark > Tello 2
BUT because TELLO is "startup" - maybe we can expect completely different and interesting development.
Honestly I dont see reasonable to upgrade any of DJIs product until CES 2019 - its like with iPhone when released, very catchy, everyone wants to touch and try.
Only reasonable move is to sell DJI brand to (for example) Intel and get the revenue right now.
I would prefer to build list of expected updates for TELLO.
Just few things and no more drones under 100 USD will exists outside PRC anymore!
Anyway UAV rules will change this soon.
Dual band is perfect of course.