Losers in 2020:
AL, IL, MI, MN, NY, OH, PA,
Possible:
NE, NJ, PA(2), RI, WV, WI
The small losers would be ranked WV, RI, NE in terms of likelihood of losing seats.
Gainers in 2020:
AZ, CO, FL, GA, NC, OR, TX(3)
Possible:
ID, UT, VA
It could end up based on whether ID surpasses NE in population (this is a necessary condition for ID to gain a seat, and NE to lose a seat, but it is not a sufficient condition).
Assuming growth rates are the same in the next 10 years as they were in the last 10 (big assumption, of course) I calculate:
Gains, in order of priority: NC, AZ, FL, NV, GA, TX (+3), VA, CO.
possible gains: OR, NC+2, FL +2, ID, MT.
Losses, in order of certainty: MI, PA, IL, RI, OH, MN, WV, NY (-2), CA.
possible losses: MI (-2), AL, NE, MA, PA(-2).