Where are you farming for VC and FS? What build are you playing?
TLDR: there is a bottle neck, bosses seem to be the best for me for VC and FS. Good luck!
I do agree there is a bottle neck. I did end up selling some belial mats and runes that I probably should have used/kept for some quick gold. I ended up running solo t6 hordes to see if I could get bartuc and if not all of it went to gold. That got me around 200m after an hour or so. That does go quick!
I think the frustration from mw is real when you run out and it stops at 4/12 or 8/12 and now the weapon or piece of gear is slightly worse.
VC and FS I usually did with bosses; with the lair boss horde keys for the undercity being nerfed (no longer drop from bosses) it has made it more difficult. However, I have farmed helltides for grig, nmd for fear, and whispers for malignant hearts. As well as trying to do all legions and bosses which drop a good amount of blood. Then farm the bosses.
I still run out especially if I am trying to mw 2/3 and 3/3 bis. With the new chaos uniques I stopped doing that and went with 1/3 and did get lucky on a few pieces that ended up being 2/3 or 3/3.
It will be interesting to see what changes they are going to make to tempering and masterworking for s11 and if this becomes an issue.
I have a feeling they are going to jack up the price but let us choose but who knows.