Many people have found themselves in a similar position. Unfortunately if your position is made redundant, your employer should then withdraw the nomination for your 186 visa and you'd need to find a new sponsor for your 457/482 visa. This is the biggest risk being on a 457/482 visa as your stay in Australia is heavily dependent on remaining with your sponsor. Your best option is probably to start looking for another sponsor immediately or see if there are any other visa options open to you.
186 visa - Temporary Residence Transition stream
Granted Dec 2013