I think there's going to be a new round of sanctions coming from the EU in the coming weeks. The DNR and LNR were declared terrorist organizations today by the Verkhovna Rada, which was mostly so the EU can do the same.
NATO won't be eager to intervene, because the risk of a multi-national conflict spiralling out of control against a nuclear power is not something that anyone wants. Sadly, it may be history repeating itself - with too little done too late before more countries are attacked in a similar fashion before it boils over.
I guess we'll have to see - but this can most definitely turn into a huge conflict.