PC
Asus announces a new ROG Ally, but it might not be a huge upgrade
The full details will be revealed in June, but from the looks of it, it will be almost the same as the original.

A new ROG Ally
Asus has revealed that they will be releasing a new ROG Ally; though it will not be called ROG Ally 2, it will be ROG Ally X, and it will be mostly the same as the first one but with an improved design and better battery life; there might be a few other improvements, and if there are, they will reveal it on June 2nd.
The video gives some details, but it was mostly done to reveal when the full announcement will occur, meaning it was an announcement for an announcement.
It's not the ROG Ally 2
The ROG Ally X will not be a full-on upgrade, as it will feature the same kind of display and the same Z1 Extreme processor, but it will have improved storage, RAM, and Ports; it will also have a few design improvements, likely a change so the SD cards do not get burned anymore when the device temperature gets too high, as well as a color change, now coming in black.
For the most part, it seems that the ROG Ally X will be a slightly better Rog Ally, but the improvements mentioned so far might not make it worth it for some unless you prefer the new design or want to upgrade from the A1 Processor version to the A1 Extreme.
"The same Z1 extreme, the same VRR display."
Speaking of processors, from the wording used on the announcement, it seems that the ROG Ally X will only come with the A1 Extreme Processor, so we might not be getting a cheaper option; this could point toward the ROG Ally X being intended to replace the A1 Extreme version of the first ROG Ally, as this one is the one more susceptible to damage the SD Card reader due to it being capable of running more demanding tasks, increasing the temperature more quickly than its counterpart.
While not exclusive to the ROG Ally X, in the announcement of the announcement, they also revealed a new upcoming User Interface that will allow you to customize how you want your games to be displayed, as well as a shortcut to help you have an easier time uninstalling your games.