No its not as you'd need to upgrade the old cylinder anyway. ASPH isn't the total way forward they are selling it as right now and I also think there will be a black market in folk fitting gas anyway after it stopped. I mean in 7 years gas boilers are banned, I just cant see that happening.
There's an awful lot of extra pipe running to do though is my point. Having my tank replaced like for like was a wheeze. New pipework I've had installed less so.
This is going to make all the combi conversions that removed water tanks a much more expensive job as gas is phased out and ASHP become "mandatory".