Hello!
Just providing some feedback on this since I know where things are headed...
There should be two separate queues (for both 4v4 and 8v8), just as it works on Live, as there is a very good reason why the queues were separated in the first place many years ago.
Some of you may remember the time when there was only one battleground queue... of seeing a full premade in the opponent team and every solo player/duo just promptly leaving the battleground and taking the deserter penalty because there is zero point in fighting fully coordinated buff sets (which effectively more than double the "stats" you're fighting against), crossheals and 3 2 1 ulti dumps.
Having a mixed group and solo queue also allows for "people" to gang up to streamsnipe streamers who happen to be solo queueing. So far battlegrounds have been a welcome respite from that sort of behaviour which goes unchecked in Cyrodiil/Imperial City... but not having a separate solo queue threatens to take that away.
So yes, I for one would like to keep the option available of queueing into solo battlegrounds when I don't have 3 other people to invite who have the required buff sets and 50k health wardens with polar winds.
It is also very important for the longevity of battlegrounds that players newer to PvP can enjoy the 8v8 mode without having to face these 4-man groups that are just looking for easy kills.
Population or queue times with separate solo/group queues (just like on Live) should not be an issue in the more fun team vs team format, especially with new rewards and ratings/leaderboards.