That isn't what the Government (currently) appears to be proposing for the ID nor has there been any information on what information/data is to be stored or that this Digital ID would supercede other forms of existing ID.
And even it was to be a fully fledged national ID, you only need to look at other countries variants to see what type of data is stored, typically this differs to other forms, and it uses, you still need driving licences and passports etc.
Again, people seem to be up in arms of this proposed ID for proving Right to Work but seem perfectly content with existing digital IDs like passports and driving licences where both contain similar data (to one and another) and a breach of either could potentially cause a person serious headaches.