I think that the dude int he background should be, say, strength level 40 or so out of 50.
Strength Level? Where did you get that from? I am fairly sure the level 50 soft cap is character level and given how all leveling still appears to be skill based, I am wondering why you said that bit about no longer levels via skills...? The 50 soft cap just makes levels above 50 much slower to gain. We know there is 280 Perks and you get a perk each level and we it sounds like it's possible to cap all attributes/skills again. Overall there will be a limit of how far you can level in total and that'll probably be based off when you cap ALL 18 skills, so you'll never be able to get all 280 perks (without the use of the console anyway) on a single character.
The way I see it, is that each time you skill up, that skill up gives you a value towards your level up, the higher the level of the skill-up the larger the value you get. As you increase in level the amount you need to level up slowly increases until level 50 when that requirement will increase dramatically to slow down leveling. However you will still be able to fulfill those requirements to a degree but to get there you will need to get all your skills up as you'll almost certainly need high skill-up values to even make an impact.
I am not sure if this is how it works but this is just an example. Say at level 1, you need say 10 points to level up. Every time you level up a skill you get 1+floor*(skill level/10) points towards the level up. If you level say destruction from level 5 to 6 you get 1 point towards the next level, but if you level say illusion from say level 18 to 19, you get 2 points towards the next level or getting a skill from level 92 to 93 gets you 10 points. What happens is that at level 48 say 97 points and at level 49 you will need say 100 points, at level 50 it suddenly increases to 150 points, then at level 51 it goes to 200 points. It suddenly increases a lot faster and harder... by level 60 you'd need in excess of 1000 points. Now I am sure this isn't how it will work in Skyrim, but I am imagining how it will work won't be too far off from this, likely a system that is far simpler that I am capable of explaining.
*floor is like rounding but ALWAYS rounds down.