Will the XBee S1 and XBee 3 communicate?

My company has several products going to market soon that were designed around the XBee S1. We’ve been running Beta tests with over 1000 existing units, however; with the discontinuation of the S1 and its non-compatibility with the SC2, I am concerned that we will have to scrap our existing models. The product change notification claims: “The Digi XBee 3 is a drop in replacement for the Digi XBee S1 PRO and is a form, fit, and functional equivalent.” Just for clarification, does this mean our existing models with the S1 will function normally with other units containing the XBee 3?