I wouldn't say that the isometric perspective is necessary to have a traditional CRPG world like Fallout. Mount and Blade does the same thing with it's overworld map and that game is third/first person. Actually, a Mount and Blade style engine would've been perfect for New Vegas, considering how much that game focused on the factions. It would fit like a glove. The overworld can deal with all the landmasses, potentially simulating massive swaths of land with random generation, while developers can make the total area of premade area equal to that of New Vegas, giving us an equal amount of actual content along with tons of randomly generated content that can be easily strung up into something entertaining. You can have both the well thought out and handcrafted quests of a CRPG with the factional wars (which come with their own systems of intrigue and strategy as well as battles) and bandit slaying of Mount and Blade. This also allows things that wouldn't fit on the Fallout 3 engine to be in New Vegas. (Imagine calling in Vertibirds or artillery, or buying a motorcycle/bicycle/horse to move around the map faster. Or, being elected as the sheriff of Primm to lead a ragtag militia to eventual glory.) I REALLY wish that a remake of New Vegas was made on the Mount and Blade engine, preferably with decent gunplay added. Honestly, that would excite me more than any Fallout 5 that Bethesda would cook up in their skinner box factory.