Some Balkan languages had lost infinitive completely and had replaced it with da+present construction or something similar, linguists think that those languages influenced nearby Slavic languages. Macedonian, Bulgarian and some south Serbian dialects  don't have infinitive at all today. In BHMS language(s) it is pretty much normal to hear both possible constructions, with infinitive and with da+present. The problem is that "dakanje" is slowly conquering the Serbian standard because of the media and the laziness of our linguists.

Less than 100 years was more than enough to banish the plural dative and locative cases, in this day and age it will take even less for infinitive to be weeded out .

So you think Serbian is trying to become a more 'simple' language? And Serbian doesn't use locative?