Wife deserts for 4 yrs,re-marriage possible without divorce?

Your friend cannot marry unless he is divorced, otherwise he'd render himself liable for one more criminal case of bigamy, besides having marriage (subsequent) voided, to expediate his divorce proceedings he can try moving an application u/s 21B r/w 151 of the CPC for speedy trial. 

Usually courts are slow to dissolve the marriages and to pass the decree for divorce, in this query it is not clear what is the position of the Divorce case, and where there is the petition for interim maintenance u/s 24 of the Hindu Marriage Act, or for the permanent allemony, there is no clear cut information about the children, many things to be adjudicated, and the quriest and his friend must wait, as mentioned  by Mr Bharat Babu.

Also remember, 21B applications seldom bear fruit!

 My view:

1. Ask your friend go for 2nd marriage after telling 2nd one of your cases.

2. If your friend wait for divorce he will lose his whole youthness.

3. By 2nd marriage your friend will fight the case with full courage to take divorce any  way if divorce not granted no one can force him to bring her back.