で vs. まで when expressing (endpoints in) time


Below is a question from a past exam for Chinese university students in
Japanese major:

> この会社に来てから、今年（で／まで）5年になります。

The answer is で. I looked up 三省堂国語辞典 and this usage of で seems to be
"ある点に達することをあらわす". My feeling is that using で maintains the probability of the
speaker's continuing to work, while まで, which I read as "until", implicates
the speaker has left this company or is going to do so.

I also performed a search in BCCWJ 中納言 for 今年まで. It yielded few results,
which, however, seem pretty normal, one of them being:

> 非難するわけではありませんけれども、この間、さきの噴火から今年までここの砂防にかけた費用等々、総額はどのくらいになっているのかなと...

I feel a nuance here, but I'm not sure if I should take it as "まで = stop, で =
continuation".




５年になります, which uses the verb なる, is an instantaneous change. 今年で means “this
year”, which is an instant.

> 今年で５年になります。
>
> (lit.) It will become 5 years (anniversary) this year.
>
> It has been 5 years.

今年まで means “up till this year”, a period of time. The verb should mean
something that continues for a duration (unlike なる). It can be used in, for
instance,

> 今年までこの会社で働きます。
>
> (lit.) I will work at this company till this year.
>
> It has been 5 years since I started working at this company (sounds like the
> speaker is quitting).




５年になります, which uses the verb なる, is an instantaneous change. 今年で means “this
year”, which is an instant.

> 今年で５年になります。
>
> (lit.) It will become 5 years (anniversary) this year.
>
> It has been 5 years.

今年まで means “up till this year”, a period of time. The verb should mean
something that continues for a duration (unlike なる). It can be used in, for
instance,

> 今年までこの会社で働きます。
>
> (lit.) I will work at this company till this year.
>
> It has been 5 years since I started working at this company (sounds like the
> speaker is quitting).

