Sure, you're not just goldfishing but a 6 card storm plus starting life-total is still 76 that your opponent needs to take 25 points out of before he's safe.
Other issues: the 4cc you mentionned. Either you need to play it and protect it for the turn or you need 4 mana you're not using storm in order to cast it before you start going off. Front loaded combos tend to be weaker than back ended ones.
It can be built up over several turns to win, which is kinda hard to do outside of Zuran Orb + Crucible shenanigans, or you can storm out with SLIGHTLY more storm count than Tendrils to win that turn.
1 spell = 1 life
2 spells = 3 life
3 spells = 6 life
4 spells = 10 life
5 spells = 15 life
6 spells = 21 life
7 spells = 28 life
8 spells = 36 life
9 spells = 45 life
10 spells = 55 life
Unless someone is pressuring your life total, 5-7 spells is enough as you gain the cumulative life on each spell. Starting on 15 life, you can "storm" 6 cards for 56 life and be on 71 without any of those cards actually gaining you life. You can also go off on multiple turns to get there but it's a bit harder though you're still only using the single source as a kill instead of a second copy of tendrils or a YWill/regrowth to reuse the first copy. Having multiples in play is obviously better.
Now you just have to protect it.
@Khahan Nope, no reserved list for Karakas. Also no reserved list for Mana Drain. It seems unlikely to me that drain would be in this set, but who knows. If they continue the eternal masters cycle like they did with MM2, then I believe at some point Drain gets reprinted.
Unlikely that Mana Drain gets reprinted at Rare, I'd say it's a no-go for this year.