Well no, by classic definition they're still here, the tradesmen, labourers etc we see every day. But things did change;
Prosperity happened. Builders, plumbers, delivery driver et al now own their own houses, have two cars and all that; not something that was so in the 1970s. Hell, they might feel middle-class. They certainly don't feel their interests are repressented by a classically working class socialist outlook, better economically educated they are no longer be drawn down the blind ally of eutopian visions. Union membership is a practical matter of getting free legal advise etc, not the "them & us" politcal statement it used to be.
Some workers are still badly off in spite of their labours, but as they don't repressent the vast majority, as they used to, their can be no class homogeneity.
The modern underclass are not the same. Industrial workers of the past saw real injustice in the imbalance of their significant labours & grinding poverty. Todays underclass can't see this; they live softer lives than ealry 20thC labourers yet do nothing for it; they have no real grievance.
So while the WC are there, they are not their in a classical, politically & socially homogenous state they were prior to the 1980s.