1. There are requires a mechanism in HRE for protecting electors from vassalization.
Now it is enough to vassalize 3-4 electors and all HRE elections is in a pocket ever.
Even if all hates you. Penalties of some type like "unlawful imperial territory" probably will be enough
to discourage the desire to turn the voters in the first priority targets for vassalization.
2. The annexation of the capital. Now this is impossible unless you can annex all
even if the capital of the enemy at your border or even far within your territory,
and the enemy does not want change the capital by itself (like Istambul by example).
Probably it should make this possible but very expensive.
Both in terms of War Store and of Infamy (or that there will be at this place in upcoming game).
For example: to annex the capital it must cost 2 - 3 or 4 times more expensive than any other province but be possible.
Now it is enough to vassalize 3-4 electors and all HRE elections is in a pocket ever.
Even if all hates you. Penalties of some type like "unlawful imperial territory" probably will be enough
to discourage the desire to turn the voters in the first priority targets for vassalization.
2. The annexation of the capital. Now this is impossible unless you can annex all
even if the capital of the enemy at your border or even far within your territory,
and the enemy does not want change the capital by itself (like Istambul by example).
Probably it should make this possible but very expensive.
Both in terms of War Store and of Infamy (or that there will be at this place in upcoming game).
For example: to annex the capital it must cost 2 - 3 or 4 times more expensive than any other province but be possible.