[Mikhail_Edoshin]

Two spaces should be a good rule for plain text formats, like Markdown or reStructuredText -- this way the parser can identify sentences and recognize the punctuation that ends an abbreviation vs the one that ends a sentence. (It's not that any parser is doing this currently, as far as I know.)

[oneeyedpigeon]

How would you handle the case in which a sentence ends with an abbreviation?

[Mikhail_Edoshin]

You cannot get everything :) It will recognize this as the end of a sentence. One use case I was thinking of was to automatically make spaces after initials non-breaking, as in "R. P. McMurphy".

[dredmorbius]

Two spaces distinguish sentences.

The abbreviation ends a sentence. It gets two spaces.