Now IBM admits they had a few years notice but did nothing about it:
I found the information stating the changes that happened in Google
stating November 17, 2014
As initially announced in November 2011, and reiterated in June of this
year, the older versions (v1, v2) of the Google Calendar API will be shut
down on November 17, 2014.
Any service dependent on v1 or v2 of the Google Calendar API will no
longer work as intended. Developers should ensure any relevant services
are utilizing v3 of the Google Calendar API prior to the shut down.
We were able to work around on the issue by using the iCalendar Feed
instead of Google TM.
But please note that this will only take the current calendar entries you
have on the Google calendar and
once you add it on the Lotus notes calendar it will not be updated with
the future entries.
This is the limitation of using the iCalendar Feed.
Rest assure that our Development Team is already aware of this issue.