I think the message of bullet cluster observation is more that dark matter should be rather cold (in order to condense in galaxies) and weakly interacting (like most of exotic dark matter candidates).
So this leaves lots of candidates.
But, it is not behaving as gas which is already a very...
I read it in some arXiv. Recently I have observed quite a lot of theoritical activity (I'm experimentalist in HEP) in this domain. It is less elegant than SUSY, but much more simpler. And it can fullfil electroweak constains.
I think this is the MOND hypothesis what you mean which is not very supported alternative.
Concerning dark energy, it has to be clear, this just means that the \Lambda CDM does not fit observations without introducing Einstein constant. So you either have to had a new energy term (like...
Few comments and questions :
- for me, one of the key measurement is that baryonic dark matter is < 3% (deuterium measurement, how far can we trush this measurement ?) => dark matter has to be something new.
- Maybe dark matter is also a mixture a different new particles.