I've got 13,772 Cubs cards from 105 different brands listed on a spreadsheet. A random number generator picked five cards, one each from the past several decades.
1900s - 1970s: 1971 Topps #280 Fergie Jenkins The Hall of Famer was at his peak in 1971. He became the first Cub to win the Cy Young Award by posing a league-leading 24 wins. He also led the league in complete games (30!) and innings pitched (325), and starts (39) while finished second in strikeouts (263). You are not going to see any pitcher match most of those season numbers any more.
1980s: 1985 Donruss #388 Thad Bosley Bosley was pinch hitter extraordinaire in 1985. He led the majors in pinch hits with 20, which was also a team record. All this earned him the coveted Skoal Pinch Hitter of the Year Award. I'm pretty sure a tobacco company can't sponsor an award any longer.
1990s: 1991 Upper Deck #314 Dave Clark Clark didn't spend the 1991 season with the Cubs; he was released towards the end of spring training. The Royals picked him up in late April and he spent most of the year with their AAA team in Omaha.
2000s: 2007 Goudey #216 Fergie Jenkins More Fergie!!
2010s: 2011 Topps Diamond Duos #MH Greg Maddux Here's a card with the Cubs other #31. This is an odd combination of players. I'm not really sure what the connection is. The card says that growing up in Iowa, Hellickson watched lots of Cubs games. When the card came out, Hellickson had a grand total of four MLB wins. That left him just 351 behind Maddux.