I think is a very good idea and here are the reasons why.
#1 For table top play it reduces time to play each turn if you have lets say 4 players +. The German and Japan player can play their turn at the same time. In our group it takes Germany/japan around 10-15 minutes to play their turns each. So, if they play at the same time you can save 10-15 minutes of game time right there. Do that for the first 4 turns as an example and you just sped up the game almost 1 hour +.
#2 It does not change game balance in the overall strategy/tactics of the game. What it does change though is that Italy can no longer “can open” for Germany, Germany now has to “can open” for Italy. That is a tactical change to the game that will effect some of the tactical approaches to the game when it comes to the invasion of Russia. Is that bad? No, it will force experienced players to just adjust and come up with new tactics for Germany/Italy and Russia. It is never bad to have experienced players looking at the game in a “new” way and how to react to the change, that is what makes the game fun.
For table top play any changes that increases the pace of the game in terms of how many minutes/hours to play turns is a big deal. This saves time in the overall picture of the game and thus I think #1 is a very good point.
I do not think option #2 will change the game if Experienced players are playing Russia/Germany/Italy. It will just change up the dynamic of the game in tactical terms with out effecting the game in a meaningful strategic way.
Now I will add one more change to “chew” on.
The OP’s change was driven by the desire to reduce the time of turns. This idea does not decrease the time of turns but puts a twist on the Allied side of who “can opens” between the USA and the UK.
Have the UK go before the USA will then force the UK to ‘can open’ for the USA instead of how it works right now which is the opposite. The theory is if we are going to change up the Axis thinking on the Europe map by moving Russia ahead of Germany, which effects the Italy/Germany tandem, you will get the same effect of having the UK move right before the USA.
Just a thought.
For our next match I think I will talk to my group and we will try this idea and see how it works and let you guys know. Iam focused on does it actually reduce the amount of time to play a turn and is it noticeable?