Ok so as someone who worked for Apple Retail from 2005 to 2009... i can say, with experience to back my assertions, that this is not going to be well when implemented.
While my entire run at apple was great and i left on a good note and enjoyed working there a lot... my only frustrations were that they always seemed to be gung ho about retail initiatives that on paper sound great and in practice SUCKED.
I was there when they announced EasyPay... which was ultra limited at first... and a few months after they initiated it, they phased out all the old registers except for one! It was horrendous (on the then bulky crash prone symbian running WinMo developed-for craptastic handheld devices) and most customers were not happy 1) being confused about where to go to check out 2) hunting for an available specialist to help them check out 3) waiting unnecessarily long for the slow ass device to connect and perform its functions. They started this new thing called "Rhonda" (help me rhonda, help help me rhonda) which was horrible because NO ONE KNEW WHERE TO GO TO SIGN IN FOR HELP or that the kinda hidden icons on the desktops of all the floor computers that said "Rhonda" meant, click here to get help.
I was there through the initiation of Concierges, and step in the right direction... then the multi colored shirts... a step in the wrong direction... and new idea after new idea that Ron Johnson - smart as he may be - drummed up as the next biggest thing in apple retail. MOST of the changes where of mixed to little value or took a long long time to perfect, causing a lot of frustrations in the process.
The genius bar queue is painful as it is and its getting worse. its hard to say what the fix is for this issue. I wont pretend like i have some magical answer to it thats so obvious or anything... its just a growing pain of apple becoming bigger and in more hands and homes.
THIS... idea seems bad however. THE geniuses i worked with were basically busy to the max handling one person at a time.. so I cant see how trying to make them juggle more pissed off people with varying issues is going to make things better. Most of the stores are physically too small to accommodate too many more people. Just about every weekend the store i worked in (which was inside a mall) had the fire marshall threatening us. Apple is on this whole minimalist kick - which means in non bigass stores, they don't rent or build spaces that have support beams in the middle of them... thus making most of their stores smaller than it really needs to be.
No matter what they try to do.. the only solution i can think of is get bigger stores where possible and hire more genii. Maybe also hire some overnight workers to stay in the store through the night and work the 3rd shift so repairs are ready for some the next day. No amount of clever optimizing with the current setup is going to help in any significant way. There is more of a chance of it backfiring or at least failing, rather than doin any significant good. IMO