Is it possible to offer both VLAs and frequency, on the same route?

Business and premium passengers want frequencies, so that they can walk up and fly. Though on some long routes, the time of day where flights make sense is limited.

But cattle class passengers want dirt cheap tickets. Something best offered in the back of A380, because of its low CASM.

However, too many half-empty A380-s is also expensive. And consolidating flights means loss of frequency.

But why should one airline on one route fly one airplane model?

Like, Airbus 330-200 has long range, low cost and sells like hot cakes. A380 upper deck is roughly as wide as A330, and shorter (maybe A310 sized). Then an airline might fit their A330s and A380s with identical first, business and premium seats on upper deck, with modest back of the bus on A330 and the whole lower deck of cattle class on A380. This way, they can cover all the frequencies with A330s, so that a businessman in a hurry can walk up and get a first class or full fare coach ticket on any flight - and add a few A380s where a huge number of discounted tourist tickets are offered.

This way, an airline cannot fly half an A380, but they can upgrade an A330 to A380, which has the same effect on capacity.

Or a mixture of B767 and B747 might be used to the same goal.

Does this cause any trouble in scheduling and marketing the flights?