However, if the trend of the interest rate is going up, the lender has a big chance to call the sale due, so they can have you refinance at a higher interest rate, and the lender can make more money.

I believe this has been a trend for the last few years and some parts of NJ are seeing astronomical appreciation because of it. 

If there is anything in decent shape just leave it by the curb for a few days and see if it disappears but if you leave it too long you might have an issue with the city. 

There are neighborhoods where I live where all the yards and professionally maintained, and others where every house is in bad shape.  

Should I expect this trend to continue in the future?

I can’t keep track of trends or spending if I do not have the data.

Does anyone know what a trend/time table of those areas being built and will it eventually be a good location for rental properties?

The main concern of any market where you want to set up a rental property is the population trends(more possible renters) and job outlook (is the city losing jobs which means a probable population decline as mentioned is important  as well as less reliable tenants to choose from).

Short of a global political cristis or a monetary system issue we should be in good shape: lending standards are still very strict (compared to pre 2008), but have eased up enough to allow for a growing market. 

It doesn't mean the least amount of competition necessarily, but rather what cities are flourishing right now, is there trends happening in the south with the boomer population reaching retirement ages,  are the wealthy flocking somewhere, etc.