"That" essentially means that you refer to things that are far away, "this" to things nearby. That can be also "emotionally or simbolically", if you want to "keep distance" (perhaps show that the thing you said is said in an impersonal or neutral way you could say "that."http://data.grammarbook.com/blog/adject ... -thanthen/This and that are singular. This indicates something physically nearby. It [i]may
also refer to something symbolically or emotionally “close.”[/i]
Sometimes you don´t want to be impersonal, rather the opposite, you want things up close and personal (it adds emphasis, as well, of course), then could use "this":
Could You Say 'No' To A Proposal Like This?
Only Love Can Hurt Like This
It´s a rule of the thumb, sort of, in real life (conversational English) perhaps there are more shadows of grey, and people may use one or the other interchangeably.
Ah, and then there is the case for sonority, as Gilson has pointed out.