I went to update the firmware on my brand new Mavic Pro last night, and in doing so a notification popped up that told me I'd be severely limited in range and altitude after the update unless I signed into the DJI Go app prior to flying. I plan to use this drone to capture footage while on backpacking trips and such in areas where I'll have no internet access whatsoever and so won't have connectivity to sign into the app. I'm very worried that this will essentially make my drone usage on these sorts of trips.
Am I right to be worried? Will I no longer be able to use my drone in remote locations if I go ahead and update the firmware? What features would updating it actually give me over running it as-is?

Just have to log in once after the update. That is all.

No issue upgrading at all.  Log in once and it remembers it.  After that it doesn't care.
There's no reason not to update.
As for what feature would be added, it depends what version you're coming from.  the .900 for example fixed a fairly nasty but with DNG portrait format photos and blue casts that was introduced in .800

Awesome, glad to hear that. I was worried that I'd lose the ability to fly the drone without reception, but I tested by going into airplane mode after upgrading & restarting my phone and everything worked. Thanks for the replies!

The real test is when you get to your destination.

We always recommend that users upgrade the latest firmware because it's the optimization to the previous one. But if your drone's now performing fine and you don't want to upgrade it, that's alright. That depends on you.

DJI Thor Posted at 2017-7-19 02:13
We always recommend that users upgrade the latest firmware because it's the optimization to the previous one. But if your drone's now performing fine and you don't want to upgrade it, that's alright. That depends on you.

Yes to this....all upgrades FW/Apps are optional, it's users preference.
If your unit is performing beautifully, why jump to unknown.
In other word "If ain't broke,Why fix it".

Unless you wanted to try and experiment w/ all those new features!