Sure, he lowered the exemption from roughly $5.5m to $3.5m, and proposed an increase in the rate to (as I recall) 65%, which is absolutely a big tax increase for maybe the richest 0.2% or so of the population - the other 99.8% don't need to worry about estate taxes, and in fact the estate tax system is a big old tax LOOPHOLE for that 99.8%. When they die, their heirs get to write up the value of inherited assets to FMV on date of death, which allows unrecognized gain on those assets (say, the family home bought in 1960 for $25,000 that's now worth $250k) to never be taxed.
But the most basic of estate planning will allow husband to use $3.5 million of the exemption available to each person under Bernie's plan, and wife to use her $3.5m, for $7m total (under Bernie's numbers). Essentially, when husband dies in your example, the first $3.5 million will NOT go to wife tax free, but to a
credit shelter trust that is taxed for estate purposes, but that can be tapped (income and/or principle) to take care of wife during her life. When she dies, whatever is in the credit shelter trust goes to the kids (usually) outside her estate and estate tax free.