3 different regulators at the output of an SMPS
Check how much current those regulators can provide. Then check what the dropped voltage is. Dropped voltage for the 7805 would be 19 volts.

Then check what the allowable power dissipation is (current x dropped voltage) then you'll conclude that the answer is NO.

For instance with the 7815 which I'm presuming you are using a well-known technique to produce 16V, the dropped voltage is 8 volts and the 30 watt demand by the load implies a load current (at 16 volts) of 1.875 A so, power dissipation is 8 V x 1.875 A = 15 watts = big heatsink if the device could supply 1.875 A (which it can't).

While you are doing those checks take a look at the L298 data sheet and note that in providing 4 amps (absolute maximum rating and to be generally avoided for a good design) this is split into 2 H bridges that can only handle 2A each. Basically if you think you can parallel two H bridges from this device you might be dissapointed.

Even if you could successfully parallel two H bridges of this type you would be dropping about 5V (worst case numbers 3.7 volts typically) in the chip at 4A and that is 20 watts to dissipate. This needs a significant heatsink - are you aware of this?