I'm really surprised by the number of luddites fearing the "great change" to water-cooling.
I'm assuming you've never heard of the KTM 640, 950, 990 models, KLR, DRZ, Vstrom, Varedero, Super Tenéré, Husqvarna, Aprilia, Highland or other venerable adventure bikes - all using liquid cooling for many moons without issue.
Those arguing that it will be a pain to fix ''in the field'' should check out the number of rallies notably THE Rallye and the number of manufacturers using liquid cooling. If CANBUS doesn't concern you - trying doing a field fix on that btw
- then liquid cooling with a tube of liquid metal in your luggage shouldn't be an issue, hell it can be done with chewing gum.
KTM, arguably the GS's main competitor, suffered nothing by running liquid cooling on its 950 and 990, the wet weight is similar to the GS. Furthermore I can't believe anyone is arguing wet weight when considering a GS - the way most people pack those things the last thing to worry about is the weight of the rad system.
Will the liquid cooling system add weight, not significantly imo because BMW knowing many owner,s predeliction with weight will shave it elsewhere, wheels, engine internals etc. Back in the day when the GSXR went from air and oil cooling to liquid cooling ( and technically still air cooling) it was a significant weight gain but bottom line Suzuki got it very wrong in the first iteration and subsequently dropped its weight significantly after that. Notably however the added weight didn't hurt sales or on or off track performance significantly despite the significant weight gain. Since the GS isn't running in any horserace the weight gain will have negligible impact.
The move to liquid cooling will have appreciable benefits moreso for BMW in terms of addressing it's environmental responsibilities than for the consumer. Rest assured the new model will sport enhancements to lure many dissenters. Just as the 12GS lured many a 1100 and 1150 owner who said never. When the 12GS was introduced many declared it ''plasticky'' and ''less planted'' and in one memorable case ''supermotard-like'' in comparison to the battle-tank 1150GSA. Many of those are now proud 12GS(A) owners without complaint.
I'm confident many here will be putting deposits down in the future - there's a new flavour of kool-aid on the market.