Bhagavatpada Sri Ramanujacarya makes the following very interesting annotation on verse 4.8 in the Gita. Particularly on the words paritrANAya sAdhunAM
sAdhava uktalakSaNadharmaSIlA vaiSNavAgresarA Sadhus or the good are those above mentioned adhearants of dharma or virtue, foremost among whom are the vaisnavas or the voteries of lord Visnu.
Well I'll just post the the English, but the sanskrt is worth looking at, especially certain phrases like, alabhamAnA aNumAtrakAlam api kalpasahasram even a fraction of a momment seems as a thousand kalpas in my absense ( to them).
While my name, deeds, and form are inaccessible to speach and thought, these voteries who have sought ultimate refuge in me, cannot get support or sustenance etc., for themselves without percieving me. They regard even a fraction of time without me as a thousand kalpas. They become broken in every limb praSithilasarvagAtrA because of the separation from me. So I am born from age to age in the forms of gods, men, etc., for protecting them by affording them the oppertunity to behold my form and acts and also to converse with me...................
Then on sambhavAmi yuge yuge
kRtatretAdiyugavizeSaniyamah api nAsti ityarthah[/I]
There are no restrictions of particular yugas such as krta, treta etc., for the appearance of divine incarnations; that's the implication.
There are some good notes on meditation as well.
One may say; what about the name Triyuga? meaning the lord who appears in three yugas. If I remember that specifies a particular type of avatara that does not manifest in the last yuga, ie, kali. But the above vizeSaniyamah api nAsti
clarifies further I guess.