There are plenty of third party analog to Dante converters out there right now. The problem is cost. Even the cheapest converters run about $50/channel and the cost can easily get up to hundreds of dollars per channel. For example, Tascam makes a 32 channel analog to Dante converter box that runs about $2000 (without the DB25 breakout cable which are also expensive) and that is on the cheaper end of the scale.
Of course when you compare that to the cost of a new console and a Dante I/O card to go with it, it seems more reasonable.