Just for kicks, I measured (in Google Maps, so not 100% accurate as it doesn't reflect all of the recent changes) the post-security walking distance from roughly the Terminal E main checkpoint, to the center of the AA side of terminal B (roughly where the main AA side checkpoint would deposit you. It's about 1.1 miles!

On the plus side, if you're someone like me who likes to get some walking in before a long time sitting, you've no doubt got close to 2 miles of concourses and corridors available, with more to come when E expands again. The 1.1 miles doesn't count going out the smaller piers like the two halves of C or the WN/AS section of B.