Yes, the real plan was to stop at the Arkhangelsk-Astrakhan line (or A-A line) as part of Generalplan Ost where they would have that obscenely large fortified frontline while they genocided or enslaved everyone west of it and conducted a perpetual bombing campaign of everything east of it. How that wasn't going to be an incredibly porous border and an insane manpower sink was never really thought through.