Noise power at receive antenna with finite transmit SNR?
Figure out the contribution of the transmitter noise at the receiver. If it is much lower than the receiver noise, then you can ignore it. If it is much larger than the receiver noise, then you can ignore the receiver noise. If the two noise sources are comparable in power, you'll have to combine them to find the overall SNR of your system.

For example, in your example (+30 dBm Tx, 10 dB SNR, 100 dB path loss), you have +20 dBm noise at the transmitter. -80 dBm arriving at the receiver. 

Your receiver noise is -174 + 80 = -94 dBm.

Since these numbers are more than 10 dB apart, you can very nearly ignore the receiver noise and your received SNR will be very close to the transmitted SNR of 10 dB.

If you really want to be very careful about things, -94 dBm is about 0.4 pW, and -80 dBm is 10 pW. So the total noise power referenced to the receiver input is 10.4 pW or -79.8 dBm. So your SNR is about 9.8 dB rather than 10 dB.

With 20 dB transmit SNR, your two noise sources will be nearly equal, requiring the full calculation of the total noise power.

With 50 dB transmit SNR, the transmitter noise will be insignificant and your calculation of 24 dB SNR based on receiver noise alone will give you the overall SNR.