Firstly, I will admit to very much liking Dads Army.
Now what will a new film be like?
The original seemed to lose something (apart from the script which the original writers distanced themselves from) when the American studio decided that Liz Fraser was a bigger draw than Janet Davies (Pikes mum) - WRONG. Janet had very nuch made the role hers so to see someone else playing it, in my mind, did not work.
In the series when James Beck (Walker) sadly died they decided to bring in a Welsh reporter, played by Talfryn Thomas. For me it did not work although John Laurie (Fraser) apparently asked the writers in a pointed way if Thomas would be in the next series as he was getting too many laughs.
So for me, one instance of changing the actress playing a part and the replacement of a character did not work - so what chance changing the actors playing the parts?
Perhaps cartoon characters of the original cast would work better.
"Don't think of them as problems, think of them as opportunities."
"OK, I think I've hit an insurmountable opportunity!"