Are you looking for a 'BECMI play style" or to be able to have every aspect of 'BECMI' rule duplicated, one for one. Which I am not sure If that is possible, nor what 5eNext will probably be.
Of course not, I was definitely thinking of playstyle, which aren't obvious to define. Thus I used some rules elements which IMHO are very typical of BECMI, at least in my limited experience. As you kind of say between the lines, not only it's going to be impossible to replicate all aspects, but also it won't make much sense. 5e will be a different game,
but it does officially have the target of supporting as many game styles as possible, including (but not necessarily limited to) those epitomizing older editions.
I picked those few elements of current 5e which IMHO contrast with what was
my at least experience with BECMI*. If 5e doesn't allow alternatives to using those (simply ignoring them might or might not work) then it might still support a BECMI-style, but somewhat less, so IMHO those points are worth to think about in order to "smoke-test" the current capabilities of 5e in replicating older editions styles.
*so for instance, cantrips at-will and rituals at-will go against my experience of playing a BECMI Wizard that has to really spare her spell slots and has to always plan ahead if to prepare those rarely used problem-solving spells (please don't anybody chime in just to say "but I hate having to do that!" -> sometimes I hated it too... here I'm trying to defend those who loved it, and the general idea that the more playstyle supported the better)
Several people have already stated this is a framework (foundation) which the rest of the game is built off of. Also remember this is an early playtest, years away from being finished. Many changes are ahead of us.
The current play test rules are nothing that I would want to play (as is), but I am waiting for for modules & more rules. Paitantly Waiting is very frustrating for myself & I'm sure, many others.
You might get the wrong idea from this thread, but currently I am quite positive that I will want to play it as is (tho some things I definitely preferred in the previous rules draft).
But the way I see the playtesting phase is that if there is one time to bring up issue it is
now. Complaining out of assuming that a certain class, module or game elements isn't available yet, particularly if it
has been announced, is not constructive; but as I said previously, "playstyles" can't always be supported by
adding something to the game... it's best to check already if the framework might make it later impossible to do such a thing, otherwise it's like giving up already on some potential.