Is it possible to determine the total amount of timelocked Bitcoin? Now that is possible to lock funds until a certain date (https://coinb.in/#newTimeLocked). How to calculate how many of all bitcoin in existence is locked until a certain date? Any service that does this?
No, it is not possible. Tools like this use P2SH, which means the script which locks the output isn't visible until it has been spent. You can determine how much might be locked (total P2SH outputs for which no script is known) and how much isn't (total non-P2SH outputs), but you can't tell much more than that.