I think they quite cunning. If I make a decision to forgo macboook now and go ahead and buy current mba/mbp then I'm like buying obsolete technology with the old USB, old thunderbolt, old charger etc etc.
I'm sure in another 1-2yrs, they will update current mba/mpb to include 2-3 ports of USB-C type and they will use the updated logic board with i5/i7 to bring both the size and weight down but with more powerful processing power.
Probably 1-2yrs is a bit far fetch. The next apple event perhaps...
otherwise how do they get that much revenue as compared to their competitors.
i understand your dilemma, i am also waiting to replace my mid-2010 mbp. for my usage, it is clear that i will definitely go for the mbp. the new macbook doesn't have enough horsepower for me although the screen resolution looks great. if the mba has that screen resolution i will take the mba.
i am wondering if they would do a redesign to the mbp at year-end.
but the fact that the refreshed mbp has thunderbolt 2, i don't think it will go away that soon. thunderbolt 2 is still far faster than usb 3.1. but it is more expensive to implement and thus mainly for pro application.
for now, i would still prefer to have magsafe for the charger.
i am pretty sure type-a will still be mainstream for the next few years. it is certainly weird to have both type-c and type-a together on a laptop.