If it funds a better and bigger Fallout 5 i'm all for it
This will entirely depend on their priorities. Any MMO-type game is a long-term development, it needs to be patched, maintained and expanded to keep the interest going which completely relies on participating player numbers and in-game purchases/subscriptions.
Happily, Bethesda applied the microtransaction model (with, a-hem, optional subscriptions) as The Elder Scrolls Online was introduced with a subscription model only which they later abandoned. I guess Fallout 76 will also be buy-to-play with microtransactions and optional subscriptions.
Personally, I have nothing against cosmetic microtransactions and purchasable expansions, however, DLC must be value-adding in my opinion.
Say this works and Bethesda is having great success with Fallout 76, don’t expect an innovative Fallout 5 anytime soon, publishers tend to sub the development out when they change their priorities… so yah.
Who knows, maybe Fallout 76 will spawn a greater single-player Fallout RPG series, maybe Fallout 76 may have a story-inspiring quest system catering towards the single players and clans (quest groups) alike. It all depends on the vision Fallout 76 may have… how they will execute, well, we will have to see.