The Playstation Vita via Remote play as an option to play FFXIV is a very enticing prospect. Video latency and control input are tolerable. However there are 2 primary issues that may need to be addressed either by Sony or Square Enix, or both.
1. Button mapping:
The current overlay mapping R2, R3, L2, L3 to the corners of the rear touchpad is not viable. They are hard to reliably input. An alternative layout should be provided as an option. A suggestion would be to use a similar layout to Bloodborne's remote play mapping. The rear touchpad is split to two halves, one for R2 and L2. R3 and L3 are assigned to the bottom corners of the touchscreen, and the Dual Shock 4 touchpad is set to the center area, not the entire screen.
2. Option to remove R/L+Dual Shock 4 touchpad shortcut to reassign skills:
This would be partially solved on the vita if the touchpad is assigned a smaller area on the touchscreen, but the option to switch off the shortcut should really be provided to avoid misclicks during gameplay, on PS4 and PSVita.
3. Keyboard input:
FFXIV being an online mmorpg benefits greatly from keyboard input. On the Playstation 4, a keyboard could be plugged in or connected via bluetooth. On the vita, it seems like a glaring omission not to include support for an onscreen keyboard. Text entry via the PS4's onscreen keyboard mechanic is extremely impractical, and the mobile playstation app requires frequent reconnection. I am not sure if the limitation for not including an onscreen keyboard comes from limitations in remote play capabilities, but the ability to use the vita's touchscreen for text entry would be a huge gain.
All in all, The Playstation Vita could be a very viable platform to play FFXIV via the Playstation 4, and these 3 issues in particular prevent the game from being played. I would like to inquire as to how these features could be suggested and followed in terms of implementation progress.