Chalk this up to someone's cut and paste error at American Way. Somebody found some artwork of the XR model and mistakenly reproduced it in the magazine. The only planes flown for Eagle by Express Jet are the CRJ200s based in LAX and DFW.
Chautauqua flies some ERJ145s (no winglets, IIRC) from ORD for Eagle. And as you both pointed out, none of the native 145s at Eagle are XRs with winglets.
There's not a chance that anyone is going to acquire new 145XRs to fly for Eagle, although it's possible that some regional airline will acquire some used ones to fly for Eagle. Not very likely, however, as Eagle has plenty of 50-seat capacity. The short-term contract for the former DL-branded CRJ200s flown by XJT was to backfill capacity lost when the 37-seater 135s were retired.
This graphic doesn't mean that 145XRs are on the way.