I think SCS should make all the money on the HoR DLC. They deserve the money and the lost money they will have with the delay and their giving to charity. They didn't have to give any money if they didn't want too, but it is so awesome they are. Especially for the Ukraine flag DLC which I will be buying as soon as it releases.
There will certainly be angry people as
@Silverwing loves to point out in comments all the time, lol!
But I think most will understand SCS's eventual decision to delay. They can work and finish HoR, then jump into their next big project, which would mean a shorter wait time between big map expansions. As well, to hold over the ETS2 crowd, work the the Austria rebuild and work on another one as well so it doesn't seem like too long a wait without new content.
As for the ATS side, they seem to be really busy with a long line of things for that coming. So I got nothing to add there.