Tell me who knows, routerboard RB953GS-5HNT-RP disappeared in Mikrotik catalog and also starting to disappear from sales. What is happening and what are the replacement options with the availability of 2-3 ports Ethernet and slot miniPCI-express (or 2-3 ports Ethernet and LTE modem with ability to connect external antennas)?

Yes, this product was discontinued earlier this year. In it's place, only RBM33G is available.

Are there plans to release RBM33G with 3 Ethernet ports?
Why it was decided to cut the functionality RBM33G so much with predecessor RB953GS-5HNT-RP?

According to official data, RBM33G has 3 ethernet ports and 2 miniPCIe ports (and a M.2 slot).

The difference is rather elsewhere: RB953GS-5HnT-RP has decent permanent storage, 2 SFP ports and built-in decent (at time of introduction) wireless interface. Pricewise RBM33G is a bargain.

I agree, I was mistaken that there are only 2 Ethernet ports. Since it has 3 Ethernet ports then it is really a good replacement.