Apple coming iOS5 update....

The coming days apple update iOS, is this effect my “aTV Flash”?

My aTVFlash is updated with the last updates 'Fire Core"installed.

What can I expect? "

If you update to iOS5 then you will ,lose your Jailbreak, and thus ATV Flash as well.

To continue using the FIreCore software you will need to wait until SeasonPass has been updated to handle iOS5.   At that point you can re-jalbreak to an iOS 5 version of the firmware, and then re-install the FireCore software.   Ideally you should have first used the new option in the FireCore Maintenance menu to back up your settings to the Cloud, so that afterwards you can restore them to avoid setting everything up from scratch again.