Just got a call from my dealer that XH-A1 will be replaced with the XH-A1s. No details on specs. Is it true?

Yes

http://www.dvinfo.net/conf/digital-video-industry-news/137222-canon-upgrades-xh-a1s-xh-g1s.html

It's a minor upgrade, similar to when the original XL1 was upgraded to the XL1s.

wondering if the same follow focus for the A1 will work on the A1s due to the much larger space between ribbing on the focus ring. (only cosmetic difference other that rear connectors)

I was under the impression no follow focuses could work with the A1 because the lens can't be geared due to the Instant AF sensor. If there's a way to use a follow focus on the A1 please let me know I'd love to use my SGPRO follow focus on it.

the af sensor is only active if you want it to be, for the extra assistance....but every lens accesory that you cant use their lens hood for or anything that blocks the sensor, like a matte box or 35mm adapter, renders that sensor useless...it only works when you activate auto focus. it's not the end of the world.

I've never used it.