First of all, Ill not compare the Assassins Creed series with The Elder Scrolls. Also, I have to say that Im a huge fan of TES and only a casual player of AC. Finally, Skyrim is a better game than AC3.

That said, its easy to see that Ubisoft went to a really open world approach on AC3 (at least when you compare with the previous AC games), and theres a couple of things that I think Bethesda can learn from AC3 for the next TES.

1 - Bigger cities: I know that on games like AC or GTA most NPCs are not interactive, but IMO its time to TES embrace that too. Skyrim is a perfect example that we cant have anymore 10 houses being called "cities". I wouldnt mind not being able to talk with every NPC if Solitude had a thousand plp walking around. On AC3, the only city I went so far is Boston, and its huge. Of course I cant enter most houses, but I think that TES games could go half way. Boston is, at least, 10 times bigger than Solitude, with 20x more people. Bethesda could try to triple cities sizes for TES VI.

2 - Movement: Winter on AC3 means that your character will walk slowly with knee deep snow if he leaves a road (this would be a perfect feature to Skyrim). Another thing is that is really fun jump around, tree to tree. I would love that my thief could do something like that on Skyrim (not so exaggerated, of course). I think that dexterity needs to come back to TES. I want thieves/rangers being able to really enjoy their agility.

3 - Combat: AC3 combat is not complex, but its pretty fun. Skyrim combat isnt boring, but is one of the weakest aspects of the game. Its time to rethink TES combat system, we need more options to attack and defend. Several games, from Dark Souls to Batman AC, already point the way.

I know some people around here dont like these big franchise games, but as far as open world games go, AC3 is a good surprise.

1. I agree wholeheartedly on this, so long as they don't go overboard with randomly generated mook NPC's for the sake of populating the city and don't sacrifice quality for quantity ( as far as size goes).

2. The movement in AC3's snow was great (from a technical standpoint, it was a pain to navigate), but something like this may not translate all too well into TES, as it is animation-intensive and first person would make it look awkward. More agile options for thiefs would be nice, though.

3. AC3's combat was one that is simple to get in to, but provides a level of depth should the player decide to use it. TES combat could certainly use an overhaul, and its something I hope Bethesda puts time in to (among other things).

No, nonono, nononoonnonononoonononononoNO!

All these aspects are what make those games what they are, so don't mix them into an Elder Scrolls game, god dammit!

You don't have to automatically assume everyone will bite your head off for comparing the two or say "Skyrim is better than AC3." It's all subjective opinion (obviously I'm saying this because I find AC3 vastly superior in terms of narrative/plot & gameplay).

1- I agree, bigger cities are a necessity in my opinion for future TES titles.
2- On this point you can't compare AC3 (where one of the three pillars of the game is navigation/free-running) to TES. That said I'd love to see something like it, but I don't kid myself into believing it will happen.
3- I agree combat needs to be changed, but definitely not in a direction any of the games you've mentioned are going. Those are all third person games, which is why those systems work. Skyrim, being first person, and having a larger variety of enemies, has to have more basic combat mechanics. For example, in AC3 you can counter pretty much any weapon- this is because every enemy archetype has a sword or a musket that can logically be countered. You can hardly counter a dragons breath or it's claws effectively.

Anyways those are my two cents. Also, TES is a big franchise game so I don't understand that last statement.

Only thing I really enjoyed from AC3 was the sailing and the multiplayer. The cities felt dead even with all that life. Bethesda could take some pointers from the animations though, they were quite nice. AC3 had a ton of clipping though. I'm sick of seeing clipping in modern games it annoys me to no end.

I disagree on the combat and the cities, while I agree with movement animations.

I think sailing would be pretty awesome in a TES game though, it was probably my favorite thing about AC3 and I thought it was going to be horrible.