In regards to FFXII HD, they probably just don't have the resources right now or it's too early to talk about.
It's definitely the later case. The game is likely already being made, but considering it's being made by the team making FFXVI, they don't want to announce it until that team takes the spotlight. Square Enix give different mainline FF teams the spotlight consecutively. First Kitase/Toriyama had it, now Tabata has it.
To break it down:
- Kitase/Toriyama team: LR FFXIII and FFX/X-2 HD Remaster promoted around the same time.
- Tabata team: FFXV and FFType-0 HD promoted around the same time.
- Ito team: FFXVI and FFXII HD Remaster promoted around the same time.
Basically, I think FFXII HD Remaster will be announced and promoted close to when FFXVI is eventually revealed to the world, which is likely in 2016. This is also the 10th anniversary of when FFXII first released. If you recall, FFX/X-2 HD Remaster was announced on the 10th anniversary of FFX.