If it would be decided that after the race the straight is too long and in the process they want to brake up the straight-90°corner-straight-90°corner character of part of the track they could do the following (without being hindered by any knowledge of the local practical and logistical situation):
1 Coming up the straight, why not use the existing round about? Avoids another 90°corner and makes it more interesting. Seems to remain enough run-off towards the water, just have to think about how to arrange the stands.
2 Shorten the main straight by 350m by rerouting the track behind the government building. Another advantage would be that you can avoid another 90°corner at T1 and reshape into two corners to allow for more interesting fights for position through corners one and two. Another advantage would be that the current again 90°corner T2 would be the second part of a sort of double kink corner.
Of course you would have to look what you would do with the pits placement and perhaps the ultra long straigth will become appreciated as the defining characteristic of the Baku Circuit and rather left as is.