Merging National Insurance into personal Income Tax has not been politically possible in the past, since the main losers would be wealthy pensioners who have high voter turnout. The pandemic has caused many working age people immense suffering, basically to protect the lives of the older generation. There is therefore a once in a lifetime opportunity of convincing pensioners they have a moral obligation to accept this reform. Merging taxes does not violate the Conservative Manifesto pledge not to raise taxes.
The employer’s National Insurance contribution, which is basically a tax on jobs, could be replaced by a tax on turnover. Many large multi-national companies (e.g. Amazon, Google, Facebook) can make their profits appear small but cannot disguise their turnover. Replacing National Insurance with a tax on turnover would ensure multi-nationals pay their fair share, create employment and help people intensive High Street stores. As it applies to all companies it would hopefully not invoke retaliatory American tariffs (as the French Digital Services Tax did).
It may be that some companies would claim that a turnover tax would render them bankrupt. So be it. If a High Street store cannot pay its rent and rates it is allowed to go bankrupt to make way for one who can.
240-11