Present progressives developing into general presents, as for example in the Chamus dialect of Maa (Mon-Khmer, Austo-Asiatic). But the latter development would only occur where a past tense already exists; if there were no past tense, the progressive would become a general imperfective (Bybee 1994: 250).
Implicationally:IF there are progressives (which develop from locative, postural or movement verb constructions), THEN they tend to develop into imperfectives or occasionally presents.
Implicationally:IF there are progressives (which develop from locative, postural or movement verb constructions), THEN they tend to develop into imperfectives or occasionally presents.