So it seems that steam keys going forward will NOT be compatible with the ED store version. Past purchases are unaffected, but suture purchases cannot be mixed and matched, which sucks pretty bad. I used to take advantage of whatever was cheaper then just play on ed store versions. Now if you buy on steam, you play on steam it seems. No more steam DCS sales for me.

Here is the ED post that relates
<table class="ModTable" style="background-color:#FFFFFF;border:1px solid #000000;border-collapse:separate;border-spacing:5px;padding:0;width:100%;color:#333333;overflow:hidden;"><tr><td class="exclamation" rowspan="2" style="background-color:#ff6060;font-weight:bold;font-family:'Times New Roman',Verdana,sans-serif;font-size:4em;color:#ffffff;vertical-align:middle;text-align:center;width:1%;">&nbsp;!&nbsp;</td><td class="rowuser" style="border-bottom:1px solid #000000;font-weight:bold;">{L_MESSAGE} {L_FROM}{L_COLON} Eagle Dynamics</td></tr><tr><td class="rowtext">Please note that the DCS: M-2000C, and all future DCS World DLC releases on Steam, will now use Steam Keys instead of Starforce keys. As such, these purchases cannot be activated on the DCS World e-Shop version. Previous purchases will not be affected.
forums.eagle.ru/showpost.php?p=3137085&postcount=86 </td></tr></table>

Yup, there was a thread about it over on the ED forums. It might be a precursor to ED abandoning the stand alone versions... which I hope is not the case.