Kevin
If the Devs were to raise the cap I imagine there would need to be some significant changes to the the entire race sim. In my experience big changes to any computer programme usually requires a prolonged testing programme and often results in unexpected bugs.
Also, it isn't just Elite that we need to consider. Raising of caps would also need to be cascaded down to the lower tiers and it does nothing to address the big dp gap between low and high level teams. L20 teams get 20dp per race, level 10 teams get 10... a difference of 10 dp per race and in the new 19 league season that means 190 points across the full season. Difference in Tech development (Boost & DRS) already cripples lower level teams, the difference in DP just adds insult to injury.
As I've said on a couple of other threads recently, IMHO a much simpler solution would be to halve the dp generated by the Design HQ and leave everything else alone. In other words no need to change the way in which CDs generate next season design, no need to modify research and the race sim would not need to change either.
So in this revised system a L20 team would only get 10dp per race (190 over a full season) meaning it would be much more difficult for a manager to max out car design, and even if it were possible the max would be reached much later in the season. This would place more emphasis on getting design balance right and a good research strategy would pay dividends. It also has the benefit of reducing the gap betwween high and low level teams. Currently the difference in dp between L20 and L10 is 10 per race, if the dp generated each race were halved the difference would only be 5.
A slight drawback is that there would need to be rounding and as a result there would never be a need to develop design HQ to 20, because L19 and L20 would both generate 10dp per race.
Of course I know this is no easy feat and nothing you could change overnight by putting other numbers into the source code. Raising the cap to 160 would mean re-balancing the cars base speeds, how much time per lap on track Y is gained by one point in stat C, etc. Also re-evaluating the max speed of the cars at the new cap and of course Pro and Rookie values would need to be looked at aswell. But with now 19 races a change is much needed.
Your approach to the problem is also a valid one. With my calculation you'd reach max stats in the big 4 before Round 15/19. That's about the same as changing the cap to 160. But as you said there would be rounding issues and every odd or even Design centre upgrade would be worthless. Unless you change the building availability from Level 11 and start awarding 1 point per level. There would have to be compensation for players who already built the previous stages though as this would be quite a drastic change.
For lower level players I am not quite sure the DP make that much of a difference, since those profit from a higher research percentage when using a high rated CD/TD combination. Much higher than a Lv. 20 manager infact. The Technology centre difference making low level managers unable to compete is a different problem though that has nothing to do with the Design Point issue that is arising with the extra races.
My focus with the issue was on leagues where there is very little discrepancy in manager AND skill level where only slightly better optimizing in your development path can give you the edge over your competitors. And either your or my or a whole other approach is needed to give each season more of this optimizing and developmental game rather than the RNG occuring mid-season once the cars even out.