Does 2g/3g rf receive circuit path work for 4g if they are in the same band?
Short answer: No.

Long answer: What did you expect? Even if in the same band, 4G OFDM and 3G CDMA / FDM signals are far far broader than 2G, and to receive GSM's GMSK, you really don't need an overly linear or large-dynamic range analog chain, very much unlike especially the 4G waveforms.

In fact, LTE is designed for IQ mixers. That's not inherently the architecture of  2G devices. Technological differences would make it overly hard to reuse a 2G architecture for 4G. What about frequency stability, non-linearity, channel hopping (including the fact that GSM transceivers have filters for 200 kHz wide channels), higher demands in coherency of LOs, worse effect of phase noise (kills especially CDMA very quickly)?

Historically, we invented a 4G that is incompatible to 2G to overcome the analog limits that the 2G receivers and transmitters pose. So, there's really not much to be won here by trying to reuse technology that is 30 years old.

Update


  I want to use fdd band8 downlink analog path(from asm to transceiver), to receive wcdma/gsm band8 signals, is this possible and practical?


For the reasons statet above, no, it's not practical.