Battery is an option but not the future and it isn't such a paradigm shift that track power will disappear entirely because it is so superior.
I can see the advantage of track power when having a very big layout with many trains and complex operations.
But for small hobbyists like me with tiny layout and few locos, track power alone is unsuitable. My love affair with railways come and go in phases. Sometimes I run trains daily and sometimes I don't even touch the trains for months. In the outdoor track, when I try to run trains after 4-5 months gap, the track becomes non-conductive and running trains became frustrating experience. Battery has resolved it. If track looks clean visually then trains always run fine with battery.
I use track power only in my tiny indoor layout. I have a slightly larger layout outdoor but use it sparingly and can only use battery because tracks are not clean to carry electric. For outdoor run I need to wear jackets, bring trains from shed, take them away after running and baby sit in the cold & rain (most of the year is like that in UK). With indoor, no such problem - trains kept on track all the time, I can just switch on power and make them run while working in adjacent room and then when I'm done just turn the power off. Hence, having option to run locos in dual mode (track + battery) is useful feature to have.
Battery does not even require tracks to be metal, which reduces cost of expanding layout outdoor as plastic, makeshift wood planks etc. can be used for tracks (for straight sections).
Manufacturers like LGB cater for those with industrial scale layouts. They are in the market to make profit, so can't blame them. I bought an LGB starter set many years back but after that I only bought used LGB/Playmobil stuff. So I am not LGB's target market.
Roundhouse makes battery locos but with very high price tags. But used LGB locos + DIY battery conversion is lot cheaper. If locos come with sockets, then the task becomes far simpler.
Piko has released one battery model (though not great looking). Some smaller scale (O/HO/OO) manufacturers have started making battery operated locos. So may be this trend will expand to G scale one day - only time will tell.
I believe there are many small G scale hobbyists like me. Not everyone joins online forums. So, there is probably an invisible market with different needs.
Now even real life trains can run in battery
