How decomissioning costs is one of the factor which needs to be considered for ceasing the production..? and Why the budget of the product showing loss for next year is not a factor for consideration of ceasing of production..?
If you cease production then you have to pay the decommissioning costs and therefore they are relevant.
Because (as I explain in the my lectures), many of the fixed overheads (if not all) will still be payable by the company. Watch my lecture on shut-down problems.