depends
If ALL estates now pay 10% INSTEAD of 40% over 500k - yes, absolutely. This is likely to generate more than the current take because of much larger base and those who are subject to IHT would not take steps to plan their estates to avoid it, 10% is acceptable.
However, I see no world where Labour would do this, they are almost certain to slap 10% on all estates in addition to current rates. Otherwise the likes of @SeaGlassDreamer will start "but what about the rich". Completely ignoring the fact that the estates have been taxed already, through income, div, CGT and other taxes, and sometime through IHTs of previous generations.
Look, the entire point of these policies is to take more tax, otherwise why bother. So people will pay more, full stop. As always, the likes of Dyson will have their arrangements, so not affected, but "the rich", who are 5-10k richer than you are, will do.