In short yes. It will technically be a 3 bed/1.75 bath house if you do that. People who have small kids will be put off because kids often don't start taking showers until they are about 9 or 10. I would do everything possible to keep it with the bath intact.

Megcblu is correct....for the most part.
Do keep the bath, but make it nice.
Tile the walls around the tub in something modern and classy and update the hardware (taps &faucets)

It'll make a difference.

I agree with Denita about checking with realtor.. If you have one tub, I would feel safe putting in a shower which often feels more modern and spacious.

Consider using glass door for the tub/shower combo for a more upscale feel.

I don't understand why realtors advise against not having a tub, even in a small home, when everyone wants to remove it but are afraid because of resale. I always wonder if the buyers are thinking "How will it affect resale if we removed the tub?"

I would not buy a house without a tub in the master bath.

Talk to the realtor. A nice large walk-in shower with rain shower head, a hand held on a rail, and body sprays can sell a home faster than one with a bland shower tub combo, or a large soaking tub. A smaller segment of buyers want both in the master. If you're going to stay in the home 10+ years, go ahead, the bath with be dated by the time you're ready to sell, and potential buyers will want to tear it out and put in what they want. If you're going to sell soon, why bother?

I rehab houses and replace tubs with super nice showers and it adds value, but I would not do want you are doing. I do that in the MBR as long as there is another tub in the house. I would not have the MBR with the only tub. I see no reason to change out a shared bathroom tub to a shower.

I totally agree with Meghan Blue. I build homes from scratch. I demolish and build new. You can see some of my homes on my profile. Now I always do one tub in master bath and one other bathroom with a tub and all my other bathrooms only showers. Reason is families have small kids who need a tub until they are old enough to shower.