Possibly - however at least initially I think both methods would be retained. A £500 limit tends to apply per industry standards, any cheques above this would need to be sent in. Some people may have problems taking pictures, eg a broken/dodgy phone camera. Some cheques might be illegible by imaging, eg if someone has poor handwriting or for whatever reason cannot be read. The bank might want to see the physical cheque where fraud has been suspected, a mistake has been made by the issuer, or the cheque has been damaged.
Then you have the issue of uncommon forms of cheque like a postal order, bankers’ draft or foreign cheque - which I’m not sure the imaging service supports.