I think alch is still a good support, even more so since you can clear jungle really easily and feed an aghs. You do have to play more conservatively but it's still a good hero.
BM still won't be good, the problem with her is that she's too extreme. You get your 12 minute radiance, you push like all fuck, you get your bkb and bots at ~16 minutes, you can't die unless they 5man you. But they can hold off your push with just 1 guy, and you suck at teamfighting and are so damn squishy no matter what. BM is just an invisible alchy, except instead of being a support she's a splitpusher.
If you play BM + NP you will win every single game, but if you don't have another splitpusher with you then you will lose every game. Also past 30 minute she's useless :/ At least with skaadi now I can tank up a bit more viably...