They are working on some sort of single life mode. I imagine it will still use control points though and have a similar structure to skirmish - just obviously max one life and more players.
Personally I never see the appeal of battle mode beyond big events. Maybe I just play too aggressively. Battle for me was always just charging in; doing as much damage as possible then waiting 10 mins while some cav or archers run away.
Something like a control point / morale system might make it more interesting and mean some sod on the other side of the map who was eating his lunch can't delay a game for another 5 mins.
That sounds like Mercenaries Battle, where the particular choices of maps and settings meant that teams either ran around in giant circles or camped both spawns, and rounds could last for ages. If people want just a large, chaotic battle of 100+ players, maybe something like that will do fine. I'd probably find it fun myself, if I can put up with all the downtime.
However, a 25v25 with a 3-minute timer and one flag system, with moderately sized maps, and no big building blocks in the centre, can result in rounds that are faster paced. There was a popular Native server called IG_Battlegrounds that lasted for several years that did this, until WBMM replaced it as the top competitive server and the MP population dwindled in 2018. The closest thing to it now is a server called The_Arena, which sometimes gets a fair amount of players, although it only uses one non-competitive map, and there are some differences in settings.
If you become a regular of Battle mode, it becomes a lot more than just "charging in; doing as much damage as possible then waiting", although you can still do that if you really want. That's basically what I did when I was an utter noob at MP, but eventually you build some awareness and learn to play more sensibly. Then it can get really satisfying, both playing individually and with teamwork.
I remember when I first played on the server, I was playing cavalry on an open map, I charged towards the enemy team from behind quickly, thinking I could take out at least one of them for one kill point, but they turned around in time and speared me down with amazing execution like some kind of Roman army. I was really impressed. And it got better and more rewarding as I got good at the game myself too.