An FFG mag would be epic. If they need an editor... well my rates are good.
In all seriousness if they ran it like White Dwarf when WD was good they could use it to 'preview' new stuff, publish quick play cut down tasters of rules sets and give away the odd acrylic or free plastic imperial assault mini etc.
The trick is distribution. You'd get it in games shops easy but getting into newsagents is expensive.
Most big chains like WHSmith in the UK.. well you have to pay them a substantial fee for them to carry your title (i know we do) and it ends up costing a lot because they pulp any back issues they dont sell... you dont get them back to stick on your website as cheap back issues etc.
Given that battlefront essentially have their own magazine after buying out 'wargames illustrated' and GW have WD then an FFG house mag would be rather cool.
Obvioulsy the problem with house mags is that they are really just big adverts and by nature partisan but as long as you know you're buying propaganda you're fine!