is cs an evergreen field or will the high salaries last only a few more years

definitely there is much demand of computer engineers in companies. but you cant say that its an evergreen field. Ones packages only depend upon 1.From where he has took his degree or 2.If one had took his/her degree from not a very good college, then he/she must be the top performer in the year of that college, to get a good package i.e. more than 8,00,000 pa. The salary packages given to computer engineers last for many years. If one has did his/her btech from IIT collage then he/she only need to be an average performer in the college. But if one has done btech from NIT or any other private college, then to get a very good package he/she has to work hard.