Is if you need to have all the connections concurrent or just one multiplexed between multiple recievers.Also do you need the connections to be duplex or simplex? the reason is that looking at the price of the philips device with 8 uarts which was $30 it would be possible to design a fpga with 8 simplex units( i.e just the reciever or just the transmitter) at a similar price point in a less complex to use device.Philips devices will use i2c because they invented that particular system but in reality it might be easier to make it a memory mapped device with control and data registers for each of the uarts (or parts there of)