Can an abusive mom and neglectful parent regain custody of thier child after signing over guardianship?

I am going to court the end of the month after a 16 month battle to keep my grandchild from going back to her mother who was convicted on felony child abuse charges and her father who was charged with child endangerment and abandonment. Recently both parents have expressed thier concerns about..."somewhere down the road we would like to raise our daughter" they are not together and are with 2 insane individuals as well. Do I have to live in fear that in a couple years-after this baby has been with me for 3 or 4 years that she will be ripped out of my life. This baby is my life!!! We have fought this battle with everything we have. If anyone can answer I would really appreciate it!!! Thanks in advance.