Just to give a short update.
Mer on Touch will most likely not come.
"Mer development stopped when Meego was announced"
"Mer^2 sounds like it's targeting N8x0 only"
"MeeGo has more long term goals"
By that sounds there is none and dont expect any community driven attempt to port Mer to HTC devices.
MeeGo wont be around for a long while so dont expect that to hit Touch Pro too as if there is any attempt to port it, it will only be focussed on newer & better devices.
BUT THERE IS HOPE
Apparently a Mer port to Touch Pro is relatively easy
"It's easy to get working,
Just get the smartq5 image, turn it into a rootfs.img, and there you go.
There might be little problems with Xfbdev, touchscreen and wifi, but it's still quite easy to do, IIRC I did Xfbdev + touchscreen + wifi in less than one day. But I've no backup of it ."
So if you are a dedicated dev, this port would be pretty useful for many people and would commend you to pick this project up.
Great HTC device + Mobile Linux + Dirt Cheap = A happy user