Still undecided x1 carbon or X270...
Just pointing out. Batteries degrade through charge cycles and deep cycling. Thinkpads don't come with proper custom charge threshold control these days. IIRC Lenovo Settings (Unlike thinkvantage power manager) only has a upper limit without a lower limit to prevent deep discharge. Unless you mod the legacy Thinkvantage power manager to work on windows 10.
It will be beyond economic repair when the battery is probably at maybe 50% of factory capacity. Be prepared to get quoted a pretty exorbitant amount for replacement. Batteries are normally under the
exclusion for extended warranty typical of any laptop manufacturer (limited to 1 year limited wty, strings attached are probably if it degrades beyond acceptable threshold, maybe less than 80% within 1 year to qualify for replacement)
Quote for keyboard below, sealed battery will be more expensive.
If you want to buy a standard ultrabook, those are the innate limitations. X270 uses a battery model that is already seeded to key thinkpad models since 2013 with good part availability than an obscure FRU/Part # that has a good chance of going EOL prematurely if not they would be screwed by corporates.
Ultimately it depends on your upgrade cycle. Think wisely. Sure, X1C is sleek like a Macbook but the workhorse models are still the bread and butter classic T5/4x0, X2X0, W/P series in the long haul.