50 year old radiant heat

I am looking for some help with our heat. We live in a 1950 ranch with radiant in the slab floor. We are in need of a new more efficient boiler(our gas bill is 400 a month). We have already had our hot water line break, and it is now run through the atic.We are also planning to add on to the house in a year or so. My question is do we hope the system hold up(and for how long?)or switch to forced air? Thanks for any help on this.