But ok, let's discuss the whole idea and "plan". I mean with that only the May 1940 POD, NOT the "sometimes 1938" one, that is just...
SO, the whole problem is that TMP obviously wanted 10 more fast divisions in June 1941, he calculated a more-or-less arbitrary number to fill the TOE, calculated a more-or-less arbitrary number what Germany could build "extra" and arrived at May 1940 at the latest, when Hitler had to decide to build those extra 10 fast divisions.
But because Hitler had a divine revelation in May 1940, orders to shift everything on the dime, voila, he has further 10 fast divisions in June 1941.
The why was never explained.
1, why he decides in May 1940 (the PzDs probably haven't even reached the sea yet!), that he would need to invade the SU in the short term?
2, why would he assume, that a one-year campaign wasn't going to cut it, and he needs at least a two-year campaign?
3, why he would feel it important to attack in 1941 instead of waiting another year and do it in late-May or Early-June 1942?
4, why would he willingly go into a two-front war for at least two years, and leave the UK unconquered in the backyard?
5, why would he suddenly assume, that further 10 fast divisions would be needed instead of the current 17+3 Bdes and the June 41 "is" of 33+3 Bdes (exl the div in North Africa)?
1, In May 1940 the SU was actually a reliable ally, and it was hoped to bring it into the war - against the French and the UK. Even if we subscribe to the idea, that Hitler wanted to exterminate the slavs, better today than tomorrow, contemplating a war against the SU for May-June 1941 and not long-term (after the situation in the West is clear, and GErmany had time to digest the conquests, say, 1943 or so) in MAY 1940 would idiotic. The complete opposite of what TMP wanted to sell.
The first indication, that the SU wasn't planning to play along was in November 1940...
2, What the SU did pre Barbarossa wasn't really awe-inspiring. It was the exact opposite. Neither in Poland, nor in Finland did the RKKA really distuingish itself, and even in the OTL-Barbarossa basically everyone - Axis, Allies, Neutrals were expecting a quick (or quickish) German victory. Till early December 1941. We could theoretically rationalize this point with "erring on the side of caution", but that would probably be the only one time Germany did that. This ties into:
3, if Germany/Hitler views the SU as a danger that would warrant an at least two-years campaign, why has to be it done 1941, and not 1942? With another year of preparation, Germany could have had much, much more than those "further 10 fast division", without the need to reorganise the whole wartime economy within a few days. In that one extra year, the situation in the West an in Africa could be cleared, probably even reaching Persia for another vector into the SU, and so forth. The only one reason for a quick, one-year campaign in 1941 was to beprive the UK of the only potential continental ally. Even that reasoning bled from a thousand wounds. If Germany planned for a two-year campaign,even the last shred of reason went out the window. And wouldn't have been contemplated without defeating the UK first.
4, OTL Barbarossa was planned as a quick grab in one year to deprive the UK of the last continental ally, before the US could lend its weight. A landing in 1940 was possible, one in 1941 may even had some reasonable chance, but even one in 1942 was only wishful thinking. 1943 it was not even a bad joke. A quick one-year-grab could be rationalized as a means to force the UK to the table for a peace in 1942 or so, but a prolonged two-years one could not. If the SU was regarded as a serious enough threat that warranted a two-years campaign, it would have been imperative to defeat the UK first. Be it in September 1940 or in early 1941.
5, We know it now, that extra troops (and supply organisations!) would have been nice to have, but hindsight is 20/20 as the saying goes.
From a strictly operational point of view, it was not possible to amass 20 German (+a lot of Rumanian) divisions somewhere north of Iasi because of bad road and railway connections in time to attack on the 22nd June. OTL, with around a third of German divisions it took ten further days.
The plan hinges on the ability to attack with two German armies on the 22nd and destroy more soviet troops and earlier than OTL. Since OTL it was not possible to mount a credible attack till the 2nd July, it would be equally impossible to mount one ten days earlier with three times the troops.
(as an aside, I haven't found any concrete idea, which divisions should be converted and relocated to Rumania. I do have the feelind, though, that troops were shuffled around, without checking, what they did OTL.)