Why is that necessary? The industry is filled with examples of relatively inexpensive games that made millions despite a small budget and small staff. And it's also filled with cautionary tales about studios overextending themselves and pouring millions and millions into a project only to see it underperform and lead to layoffs, closures, and, in some cases, bankruptcy. If anything, the status quo is the less sustainable option.

It's not the worst idea ever, and your logic makes sense, but if DLC is done right, its the ability to add more to a game you already love. You shouldn't be fforced to pay extra for a game you may not even enjoy.

This :)

And this :)

For a series like battlefield I'm paying $70 for the base game and $40 for premium which is $110 in total. So of course I'd pay 80$ but that would never happen because all the expansions you get are worth an awful lot more then $10 extra.

If people paid for dlc and similar "up front", then most deva would have little incentive to make the future content as good as possible - matter of fact it would be the opposite since they already have your money

I would go for option C: The game complete with everything from the start for $60, like they should be...

My ideal situation is that expansions and DLCs MUST NOT be either material taken away from the original release, nor on disc unlockable contents, launch price must be $60 or lower ($55 or lower on PC, same figure in Euros, but including VAT, in EU), and at the same price some time after the first launch they must release an enhanced edition including the main expansions and DLCs released in the meantime, for the most ambitious games, if they match a lot my tastes, the enhanced edition will be my choice, while for example, although I like Morrowind, its somehow errand-boy gameplay if one, like me, likes to complete as many sidequests as possible, exacerbated in the Game of the Year Edition, made me choose a discounted plain initial release of Skyrim, instead of the Legendary or the Special one.
For the Witcher 1 and 2 OTOH, I chose the Enhanced Edition, and unlike usual, I bought them quite early, when they still were full priced, just with the usual 10-15% discount made by most large shops also on new titles, I wanted to reward dev and publisher for their DRM-free choice.
But $80 or 80€ no, never, neither for the best games, no way in hell.

Only if a developer was absolutely clear on the future release schedule of additional content

Personally, probably not, as I don't usually care for DLC and usually get games soon after launch, typically when they are cheaper.