If your old receiver has arc then i think theres not much you can benefit from a newer receiver. Im coming from the idea that your streaming data will come from a smart tv then going into the receiver. Old Arc and optical are the same (soundwise - internet info) so arc may not even be necessary. No dd+ for optical but you have 20k still in the bank. If you have separate 4k devices then maybe an upgrade is a good path to take. Especially if one of your plans is adding speakers for atmos.