Most likely it would create quite a few problems for BRP holders even if an online check on UK border will be flawless. 1. To apply for a visa (e.g. Schengen o

Most likely it would create quite a few problems for BRP holders even if an online check on UK border will be flawless. 1. To apply for a visa (e.g. Schengen one) one need a proof of residence. While EU hopefully will start accepting online proof (may be a couple year later, EU bureaucracy is slow) other countries likely will stop accepting visa applications from UK residents in the UK. 2. Before non-UK citizens can checkin on a flight to the UK from another country they must show either a visa or a BRP. Knowing how some countries operate (paper, paper, paper) they would likely will ignore this online stuff and refuse to board without a physical proof.