Correction for bridge: abutments are #30 and 32, pontic will be #31.
The negative implications of leaving the gap between #30 and #32 (If you have it). Will be so called drifting on that arch and passive eruption on the arch opposite it.
Drifting will cause #32 take position/incline itself to the position of #31.
Here is a minute long video about drifting, like in your case mesial one:
http://www.checkdent.com/en/videos/mesial-drift-120.html
Passive eruption will cause the tooth on the opposite arch to continue moving lower and lower. In this case it will be #2 (Mx, 2nd Molar), as there is nothing to occlude with it will continue moving lower, and lower.
The other option if you do not want to have an implant is a bridge. The only concern for the bridge is that you will have to have your #30 and #32 prepped (shaven down), so the crowns can be put on it in order to help hold the abutment of #31.
Implants are thought to be not as good, but close enough to our natural teeth. You mention that your tissue is in good condition, you probably do not smoke - so the dentists recommended implant.
Some may allow for a payment which can be spread apart, so ask yours about it.
Hi....they are really pushing the implants these days, and as nice as they are....it's very expensive. You have other options and tell them you want to know what these options are...or find a new dentist who cares more about you than the money!