I've recently come to the conclusion that I don't really like EU IV all that much. I've only put 64 hours into it in contrast to the 209 I've sunk into Vicky 2. I really think that, despite the array of rather simple features layered on top through DLC, EUIV is really all about expanding a blob of color on a map. Admittedly I haven't bought Mandate of Heaven, Mare Nostrom or the Rights of Man, so maybe these would improve the game somewhat.
There are two things you need to simulate right to make me feel like I am actually controlling a real nation: Government, Economy and Population, Victoria simulates these better than any other Paradox game. EUIV, to the extent that it simulates these things at all, presents us with rather dumnbed-down alternatives. If they did extend the timeline to encompass the Victorian era, I do not believe they would remake Victoria's mechanics, expanding your blob will still be the order of the day, and most we would get is a few simple mechanics + a fifth tier of unit models.
It's always felt to me that the only interesting things to do in EUIV is going to war or preparing for war, Vicky 2 made peacetime gameplay just as interesting, with the complex pop system, the array of reforms that could be passed, the way governments were formed, the jostling between different parties the spread of movements and the rise of new issues, the economic system and the building of factories, the diplomatic system, allowing you to create mini-cold wars in order to expand your sphere at the expense of other GPs and so on...
All of that made peacetime and internal politics in Vicky just as, if not more compelling than anything in EUIV. I don't see how bringing the Victorian era in EUIV would emulate that, it would most likely be a glorified timeline extension.