Lol.... Yes it could happen, but it won't. A great majority of the hash power apparently supports the fork and has done so for a while now: https://cryptap.us/myr/myrstat/
I've heard that Myriad is the first coin to actually make use of this consensus system requiring the last 750/1000 blocks. It would be available to DGB too if they upgrade to a more recent Bitcoin code base. If Qubit miners decide to keep on the old chain, sure they can.... but I can't see them getting much support from the community. In fact, right now 100% of Qubit blocks are hard-fork blocks.... so Qubit ASIC miners are firing themselves... or more likely they simply downloaded the latest wallet without reading what it does because they are just trying to mine and dump as many MYR/XMY as quickly as they can.