I am not knowledgable on the technical side to consoles and pc and the performance limits. Whether memory becomes an issue etc

But what I have noticed is how slower and more glitchy Skyrim gets every time I add more dlc. Loads screens take longer and often when I visit a Hearthfire house I'm scared the game will freeze.

I've turned off my auto save and reduced the number of game saves to a minimal which helps but even then I have problems.

Noticing this I am wondering if this something to do with memory needed and whether Skyrim can handle much more DLC. Would it be more logical to make a spin-off game like Fallout: New Vegas was to Fallout 3 or TESA: Redguard was to TES II: Daggerfall?
(Similar to the way the Liberty City games like "the Ballad of Gay Barry" were to GTA IV)

I think that would depend on the DLC, more DLC like Dragonborn would be loaded mostly separately from the main game... were as DLC like Dawnguard would add more stuff on top of the main game taking more system resources. Rather how much would really cause an issue is yet to be seen.