Kim,
While I can see the truth in this statement, I think it is still perpetuating the same kinds of problems with emphasis.
If by "problems with emphasis" you mean that a particular approach (e.g. Boice's "back to the cities" call) may be either poorly motivated or inappropriate in a particular situation (geographical or individual), of course I agree we must have the attitude "you in your small corner, and I in mine" wherever we are led, and I do not mean to imply that many are not exactly where the Lord wants them!
But while there will always be a diversity of levels of diversity(!) in our churches, I continue to feel the cultural playing fields of suburban vs urban churches are so vastly different that without radical effort to overcome it, the inertia of status quo swallows up any comfort one might have from the other.
I just did a little census research on our own situation here in NYC and a major suburban area. Hopefully a graphical representation will highlight the different playing fields. (Note, the church info is estimated).
1 letter equals 50,000 people
W=White
B=Black
H=Hispanic
A=Asian
1 letter equals 100 churches
R=Reformed (more or less!)
E=Evangelical (much less reformed)
P=Pentecostal
Bergen County, NJ (suburban):
People:
WWAWWBWWHWWWWHWWWAW
Churches:
EEPEREEPEE
New York, NY (urban)
People:
BWHWAWHBWHBWHABWHBHW
WBHAHWWBHWBBWHWBHBWA
AWBHBWHWBWAHWWHBHWHB
HBWHAHBAWWBHWWBWHBBW
AWHBBBWHWWHBWHBWHAWH
HAWHBWHWBWAWBHBWHBBW
BHWBWHWWBHHHWAWBWAHB
WABHHBWWAHBWWBHBWBHW
Churches:
EPEPEEPPEE
PEPEPEEEEP
PEEPPEPEEP
EPEPEPEEEP
EPEPPEEPEE
PEPEERPEEP
PEEPEEEEPP
The real imbalance imo is what I think Kyle alluded to ("What can we do to make Christians of minority backgrounds feel a part of the family and not alienated by cultural and economic circumstance?") and TJ stated outright: that there simply is not a noticeable Reformed presence among the vast majority of blacks and hispanics. And a huge element of "cultural and economic circumstance" is the fact that most minority subcultures live in urban, not suburban, settings, which does point to an appropriate biblical motivation, namely, ministry to the poor.